A continuum density field formulation with particle-scale resolution is constructed to simultaneously incorporate the orientation dependence of interparticle interactions and the rotational invariance of the system, a fundamental but challenging issue in modeling the structure and dynamics of a broa...

[Phys. Rev. B 97, 180102(R)] Published Fri May 25, 2018

]]>The effective screening of the polarization bound charge is a prerequisite to stabilize the ferroelectricity in ferroelectric thin films. Here, by combining annular bright field imaging and electron energy-loss spectroscopy (EELS) in an aberration-corrected scanning transmission electron microscope ...

[Phys. Rev. B 97, 180103(R)] Published Fri May 25, 2018

]]>We predict mechanochemical formation of heterogeneous diamond structures from rapid uniaxial compression in graphite using quantum molecular dynamics simulations. Ensembles of simulations reveal the formation of different diamondlike products starting from thermal graphite crystal configurations. We...

[Phys. Rev. B 97, 184106] Published Fri May 25, 2018

]]>Standard approaches to magnetomechanical interactions in thermal magnetic crystalline solids involve Landau functionals in which the lattice anisotropy and the resulting magnetization easy axes are taken explicitly into account. In glassy systems one needs to develop a theory in which the amorphous ...

[Phys. Rev. B 97, 174105] Published Thu May 24, 2018

]]>$\mathrm{C}{\mathrm{a}}_{3}\mathrm{T}{\mathrm{i}}_{2}{\mathrm{O}}_{7}$ is an experimentally confirmed hybrid improper ferroelectric material, in which the electric polarization is induced by a combination of the coherent $\mathrm{Ti}{\mathrm{O}}_{6}$ octahedral rotation and tilting. In this work, we investigate the tuning of ferroelectricity of $\mathrm{C}{\mathrm{a}}_{3}\mathrm{T}{\mathrm{i}}_{2}{\mathrm{O}}_{7}$ using isovalent substitutions o...

[Phys. Rev. B 97, 184105] Published Wed May 23, 2018

]]>We propose a computational methodology capable of harvesting isothermal heat and entropy change in molecular dynamics simulations. The methodology is applied to study high-frequency dynamics of the electrocaloric effect (ECE) in ferroelectric ${\mathrm{PbTiO}}_{3}$. ECE is associated with a reversible change in tem...

[Phys. Rev. B 97, 184104] Published Mon May 21, 2018

]]>We perform first-principles calculations to investigate the phase stability of boron carbide, concentrating on the recently proposed alternative structural models composed not only of the regularly studied ${\mathrm{B}}_{11}{\mathrm{C}}^{p}$(CBC) and ${\mathrm{B}}_{12}$(CBC), but also of ${\mathrm{B}}_{12}$(CBCB) and ${\mathrm{B}}_{12}({\mathrm{B}}_{4}$). We find that a combination of the ...

[Phys. Rev. B 97, 174104] Published Fri May 18, 2018

]]>Topological elastic waves have recently emerged as an exciting interdisciplinary field which is still mainly focused on low-dimensional systems. Here we propose phononic topological node lines emerging from three-dimensional mechanical metacrystals. The resultant ribbon- or drumhead-like phononic ed...

[Phys. Rev. B 97, 180101(R)] Published Fri May 18, 2018

]]>Stable compounds in the Cr-H system have been synthesized through a direct reaction of chromium and hydrogen in a laser-heated diamond-anvil cell and investigated using synchrotron x-ray diffraction up to $120\phantom{\rule{0.28em}{0ex}}\mathrm{GPa}$. The sequence of hydrides CrH, ${\mathrm{Cr}}_{2}{\mathrm{H}}_{3}$, and ${\mathrm{CrH}}_{2}$ has been observed by increasing pressure....

[Phys. Rev. B 97, 184103] Published Fri May 18, 2018

]]>Antiferroelectric-to-ferroelectric transitions in squaric acid are simulated by computationally applying a static electric field. Depending on the direction of the electric field, two different metastable ferroelectric (and piezoelectric) phases have been found. One of them corresponds to the experi...

[Phys. Rev. B 97, 184102] Published Mon May 14, 2018

]]>The phase stability of icosahedral boron subselenide ${\mathrm{B}}_{12}{\left({\mathrm{B}}_{1-x}{\mathrm{Se}}_{x}\right)}_{2}$, where $0.5\le x\le 1$, is explored using a first-principles cluster expansion. The results shows that, instead of a continuous solid solution, ${\mathrm{B}}_{12}{\left({\mathrm{B}}_{1-x}{\mathrm{Se}}_{x}\right)}_{2}$ is thermodynamically stable as an individual line compound at the composition of ${\mathrm{B}}_{\mathrm{9...}}$

[Phys. Rev. B 97, 174103] Published Fri May 11, 2018

]]>The effect of pressure on the structural, vibrational, and electronic properties of Mg-doped Cr bearing spinel $\mathrm{C}{\mathrm{o}}_{0.5}\mathrm{M}{\mathrm{g}}_{0.5}\mathrm{C}{\mathrm{r}}_{2}{\mathrm{O}}_{4}$ was studied up to 55 GPa at room-temperature using x-ray diffraction, Raman spectroscopy, electrical transport measurements, and *ab initio* calculations. We found that the am...

[Phys. Rev. B 97, 174102] Published Thu May 10, 2018

]]>The understanding of the atomistic origin of the morphotropic phase boundary (MPB) occurring in composition-temperature phase diagrams of ferroelectric solid solutions is a key topic in material science because materials often exhibit anomalous properties at the MPB. Here we reveal mesoscopic-scale ...

[Phys. Rev. B 97, 184101] Published Thu May 03, 2018

]]>We have investigated the effect of transition-metal dopants on the local structure of the prototypical $0.75\mathrm{Pb}\left({\mathrm{Mg}}_{1/3}{\mathrm{Nb}}_{2/3}\right){\mathrm{O}}_{3}\text{\u2212}0.25{\mathrm{PbTiO}}_{3}$ relaxor ferroelectric. We find that these dopants give rise to very different local structure and other physical properties. For example, when Mg is partially substi...

[Phys. Rev. B 97, 174101] Published Tue May 01, 2018

]]>We predict that the application of biaxial tensile strain will uncover an antiferromagnetic metallic *hidden phase* in ${\mathrm{Sr}}_{3}{\mathrm{Ru}}_{2}{\mathrm{O}}_{7}$. By using hybrid density functional theory we applied uniaxial and biaxial strains and identified a variety of phases. We found that tensile strain can reduce by up to half t...

[Phys. Rev. B 97, 134116] Published Mon Apr 30, 2018

]]>The physical properties of the spinel ${\mathrm{LiGaCr}}_{4}{\mathrm{S}}_{8}$ have been studied with neutron diffraction, x-ray diffraction, magnetic susceptibility, and heat capacity measurements. The neutron diffraction and synchrotron x-ray diffraction data reveal negative thermal expansion (NTE) below 111(4) K. The magnetic ...

[Phys. Rev. B 97, 134117] Published Mon Apr 30, 2018

]]>We study linear vibrational modes in finite isostatic Maxwell lattices, mechanical systems where the number of degrees of freedom matches the number of constraints. Recent progress in topological mechanics exploits the nontrivial topology of BDI class Hamiltonians in one dimenson and arising topolog...

[Phys. Rev. B 97, 134118] Published Mon Apr 30, 2018

]]>A general procedure is developed to investigate the elastic response and calculate the elastic constants of stressed and unstressed materials through continuum field modeling, particularly the phase-field crystal (PFC) models. It is found that for a complete description of system response to elastic...

[Phys. Rev. B 97, 144112] Published Mon Apr 30, 2018

]]>Soft phonon modes describe a collective movement of atoms that transform a higher-symmetry crystal structure into a lower-symmetry crystal structure. Such structural transformations occur at finite temperatures, where the phonons (i.e., the low-temperature vibrational modes) and the static perfect c...

[Phys. Rev. B 97, 134114] Published Fri Apr 27, 2018

]]>Using Landau-Ginzburg-Devonshire (LGD) theory for $\mathrm{BiFe}{\mathrm{O}}_{3}$ dense fine-grained ceramics with quasispherical grains and nanosized intergrain spaces enriched by elastic defects, we calculated a surprisingly strong size-induced increase in the antiferromagnetic transition temperature caused by the joint a...

[Phys. Rev. B 97, 134115] Published Fri Apr 27, 2018

]]>Despite silicon being of great technological importance, an understanding of its behavior across the phase diagram is still lacking, especially near liquid-solid coexistence. The difficulty in describing silicon near coexistence from first principles lies in discriminating between the metallic and c...

[Phys. Rev. B 97, 140103(R)] Published Thu Apr 26, 2018

]]>Systematic *ab initio* structure simulations have been used to explore the high-pressure behavior of nitinol (NiTi) at zero temperature. Our crystal structure prediction and first-principles calculations reveal that the known $B19$ phase is dynamically unstable, and an orthorhombic structure (*Pbcm*) and ...

[Phys. Rev. B 97, 140104(R)] Published Thu Apr 26, 2018

]]>Water inside a nanocapillary exhibits unconventional structural and dynamical behavior due to its ordered structure. The confining walls, density, and lateral pressures control profoundly the microscopic structure of trapped water. Here we study the electrostriction of confined water subjected to pr...

[Phys. Rev. B 97, 144111] Published Wed Apr 25, 2018

]]>This work reports the changes in structure and lattice dynamics induced by substituting the Jahn-Teller-active $\mathrm{M}{\mathrm{n}}^{3+}$ ion by the Jahn-Teller-inactive $\mathrm{F}{\mathrm{e}}^{3+}$ in $\mathrm{TbM}{\mathrm{n}}_{1\text{\u2212}x}\mathrm{F}{\mathrm{e}}_{x}{\mathrm{O}}_{3}$ over the full composition range. The structural analysis reveals that the amplitude of the cooperative Jahn-Teller distortion decre...

[Phys. Rev. B 97, 144110] Published Thu Apr 19, 2018

]]>Domain switching and lattice strain are known to be important processes contributing to the large electromechanical response observed in perovskite-based piezoelectrics. However, there is a lack of clarity regarding the coupling between the two phenomena, and the factors which influence this couplin...

[Phys. Rev. B 97, 134113] Published Wed Apr 18, 2018

]]>Fine-grained diamond, or high-density carbon (HDC), is being used as an ablator for inertial confinement fusion (ICF) research at the National Ignition Facility (NIF). Accurate equation of state (EOS) knowledge over a wide range of phase space is critical in the design and analysis of integrated ICF...

[Phys. Rev. B 97, 144108] Published Wed Apr 18, 2018

]]>Electron density distributions of $\mathrm{PbTi}{\mathrm{O}}_{3},\mathrm{BaTi}{\mathrm{O}}_{3}$, and $\mathrm{SrTi}{\mathrm{O}}_{3}$ were determined by synchrotron x-ray powder diffraction up to 55 GPa at 300 K and *ab initio* quantum chemical molecular orbital (MO) calculations, together with a combination of maximum entropy method calculations. The intensity profiles of...

[Phys. Rev. B 97, 144109] Published Wed Apr 18, 2018

]]>We report the observation of multiphoton photoluminescence excitation (PLE) below the resonant energies of nitrogen vacancy (NV) centers in diamond. The quadratic and cubic dependence of the integrated fluorescence intensity as a function of excitation power indicates a two-photon excitation pathway...

[Phys. Rev. B 97, 134112] Published Tue Apr 17, 2018

]]>Identification of kinetic and thermodynamic factors that control crystal nucleation and growth represents a central challenge in materials synthesis. Here we report that apparently defect-free growth of ${\mathrm{La}}_{2}{\mathrm{MnNiO}}_{6}$ (LMNO) thin films supported on ${\mathrm{SrTiO}}_{3}$ (STO) proceeds up to 1–5 nm, after which it is di...

[Phys. Rev. B 97, 134110] Published Fri Apr 13, 2018

]]>The high-pressure behavior of monoclinic ($P{2}_{1}/c$) $\alpha $-chalcocite, ${\mathrm{Cu}}_{2}\mathrm{S}$, was investigated at ambient temperature by single-crystal x-ray diffraction, electrical resistance measurements, and optical absorption spectroscopy up to 16 GPa. The experiments were complemented by density-functional-theory-based...

[Phys. Rev. B 97, 134111] Published Fri Apr 13, 2018

]]>X-ray powder diffraction experiments using resistively heated diamond anvil cells have been conducted in order to establish the phase behavior of antimony up to 31 GPa and 835 K. The dip in the melting curve at 5.7 GPa and 840 K is identified as the triple point between the Sb-I, incommensurate Sb-I...

[Phys. Rev. B 97, 144107] Published Fri Apr 13, 2018

]]>By combining molecular dynamics (MD) simulations with phase-field (PF) and phase-field crystal (PFC) modeling we study collision-controlled growth kinetics from the melt for pure Fe. The MD/PF comparison shows, on the one hand, that the PF model can be properly designed to reproduce quantitatively d...

[Phys. Rev. B 97, 144105] Published Thu Apr 12, 2018

]]>The authors discuss a lower bound of nonlocal entanglement entropy (a generalization of topological entanglement entropy). The lower bound applies to Abelian conventional topological order as well as to type-I and type-II fracton models. It provides the physical intuition that each type of topological excitation, created by a deformable string, membrane, or fractal operator, gives a contribution to the nonlocal entanglement entropy. For fracton models, the lower bound is geometry dependent; it can take extensive values.

[Phys. Rev. B 97, 144106] Published Thu Apr 12, 2018

]]>The identification of phases of matter is a challenging task, especially in quantum mechanics, where the complexity of the ground state appears to grow exponentially with the size of the system. Traditionally, physicists have to identify the relevant order parameters for the classification of the di...

[Phys. Rev. B 97, 134109] Published Wed Apr 11, 2018

]]>The conventional Kibble-Zurek scaling describes the scaling behavior in the driven dynamics across a single critical region. In this paper, we study the driven dynamics across an overlapping critical region, in which a critical region (Region A) is overlaid by another critical region (Region B). We ...

[Phys. Rev. B 97, 134108] Published Tue Apr 10, 2018

]]>We present an experimental study for polycrystalline samples of the diluted magnetic semiconductor $\mathrm{M}{\mathrm{n}}_{x}\mathrm{G}{\mathrm{a}}_{1-x}\mathrm{N}\phantom{\rule{4pt}{0ex}}\left(x\le 0.04\right)$ in order to address some of the existing controversial issues. X-ray and neutron diffraction, x-ray absorption near-edge structure, and electron paramagnetic resonance experiments wer...

[Phys. Rev. B 97, 140102(R)] Published Tue Apr 10, 2018

]]>Low-dimensional ferroelectricity has attracted tremendous attention due to its huge potential in device applications. Here, based on first-principles calculations, we predict the existence of spontaneous in-plane electrical polarization and ferroelectricity in monolayer $\beta $-GeSe, a polymorph of GeSe w...

[Phys. Rev. B 97, 144104] Published Tue Apr 10, 2018

]]>The nature of the glass transition is a fundamental and long-standing intriguing issue in the condensed-matter physics and materials science community. In particular, the structural response by which a liquid is arrested dynamically to form a glass or amorphous solid upon approaching its freezing te...

[Phys. Rev. B 97, 134107] Published Mon Apr 09, 2018

]]>Multiple shock reverberation compression experiments are designed and performed to determine the equation of state of neon ranging from the initial dense gas up to the warm dense regime where the pressure is from about 40 MPa to 120 GPa and the temperature is from about 297 K up to above 20 000 K. T...

[Phys. Rev. B 97, 140101(R)] Published Fri Apr 06, 2018

]]>Ground-state epitaxial phase diagrams are calculated by density functional theory (DFT) for ${\mathrm{SrTiO}}_{3},{\mathrm{CaTiO}}_{3}$, and ${\mathrm{SrHfO}}_{3}$ perovskite-based compounds, accounting for the effects of antiferrodistortive and $A$-site displacement modes. Biaxial strain states corresponding to epitaxial growth of (001)-oriente...

[Phys. Rev. B 97, 134103] Published Thu Apr 05, 2018

]]>In an electron backscatter diffraction pattern (EBSP), the angular distribution of backscattered electrons (BSEs) depends on their energy. Monte Carlo modeling of their depth and energy distributions suggests that the highest energy BSEs are more likely to hit the bottom of the detector than the top...

[Phys. Rev. B 97, 134104] Published Thu Apr 05, 2018

]]>The stability of GeTe in rhombohedral ($R3m$), face centred cubic ($Fm3m$), and simple cubic ($Pm3m$) phases has been studied using density functional perturbation theory. The rhombohedral phase of GeTe is dynamically stable at 0 GPa, while $Fm3m$ and $Pm3m$ phases are stable at 3.1 and 33 GPa, respectively. ...

[Phys. Rev. B 97, 134105] Published Thu Apr 05, 2018

]]>Using classical Monte Carlo simulations, we study a simple statistical mechanical model of relevance to the emergence of polarization from local displacements on the square and cubic lattices. Our model contains two key ingredients: a Kitaev-like orientation-dependent interaction between nearest nei...

[Phys. Rev. B 97, 134106] Published Thu Apr 05, 2018

]]>There has recently been renewed interest in improper ferroelectricity due to the discovery of a “hybrid” mechanism by which two nonpolar lattice modes couple to a third polar mode. Here, the authors demonstrate that the polar ground state of perovskite HgMn${}_{3}$Mn${}_{4}$O${}_{12}$ emerges due to electronic instabilities that drive charge and orbital ordering on the A- and B-sites. These order parameters couple to polar displacements (P) in a manner conceptually similar to hybrid improper ferroelectricity. The results open up a possible route for electronic control of orbital ordering - an appealing prospect given the technologically important properties dependent on such states.

[Phys. Rev. B 97, 144102] Published Thu Apr 05, 2018

]]>This paper introduces an approach based on transition potentials for inelastic scattering to understand the underlying physics of electron magnetic circular dichroism (EMCD). The transition potentials are sufficiently localized to permit atomic-scale EMCD. Two-beam and three-beam systematic row case...

[Phys. Rev. B 97, 144103] Published Thu Apr 05, 2018

]]>Hybrid van der Waals heterostructures constructed by the integration of organic molecules and two-dimensional (2D) transition metal dichalcogenide (TMD) materials have useful tunable properties for flexible electronic devices. Due to the chemically inert and atomically smooth nature of the TMD surfa...

[Phys. Rev. B 97, 134102] Published Wed Apr 04, 2018

]]>Consecutive stochastic 90° polarization switching events, clearly resolved in recent experiments, are described by a nucleation and growth multistep model. It extends the classical Kolmogorov-Avrami-Ishibashi approach and includes possible consecutive 90°- and parallel 180° switching events. The mod...

[Phys. Rev. B 97, 144101] Published Wed Apr 04, 2018

]]>We have measured the equilibrium melting pressure of helium-4 as a function of the crystal size. Negative compressibility of a liquid with an inclusion of solid seed is predicted theoretically and verified experimentally with helium-4 crystal-superfluid system at 0.15 K. This two-phase system is sho...

[Phys. Rev. B 97, 134101] Published Mon Apr 02, 2018

]]>Solid krypton (Kr) undergoes a pressure-induced martensitic phase transition from a face-centered cubic (fcc) to a hexagonal close-packed (hcp) structure. These two phases coexist in a very wide pressure domain inducing important modifications of the bulk properties of the resulting mixed phase syst...

[Phys. Rev. B 97, 094115] Published Fri Mar 30, 2018

]]>To date, the high-temperature phase transition *R3m*$\text{\u2212}Fm\phantom{\rule{0.83328pt}{0ex}}\overline{3}\phantom{\rule{0.83328pt}{0ex}}m$ in GeTe is commonly believed to be second-order displacive with an anomalous volume contraction at the phase transition temperature, ${T}_{PT}$, from diffraction measurements. Three main results are here reported: (i) the phase transition is accompan...

[Phys. Rev. B 97, 094116] Published Fri Mar 30, 2018

]]>The paper theoretically studies the possibility of using the effects of phonon interference between paths through different interatomic bonds for the control of phonon heat transfer through internal crystal interfaces and for the design of phonon metamirrors and meta-absorbers. These metamirrors and...

[Phys. Rev. B 97, 094117] Published Fri Mar 30, 2018

]]>An atomistic effective Hamiltonian is used to investigate electrocaloric (EC) effects of $\mathrm{Pb}\left({\mathrm{Mg}}_{1/3}{\mathrm{Nb}}_{2/3}\right){\mathrm{O}}_{3}$ relaxor ferroelectrics in its ergodic regime, and subject to electric fields applied along the pseudocubic [111] direction. Such a Hamiltonian qualitatively reproduces (i) the electric field-ver...

[Phys. Rev. B 97, 104110] Published Fri Mar 30, 2018

]]>Topological materials provide an exclusive platform to study the dynamics of relativistic particles in table-top experiments and offer the possibility of wide-scale technological applications. ZrSiS is a newly discovered topological nodal-line semimetal and has drawn enormous interests. In this pape...

[Phys. Rev. B 97, 094112] Published Wed Mar 28, 2018

]]>The electrocaloric effect in ferroics is considered a powerful solid-state cooling technology. Its potential is enhanced by correlation to the inverse electrocaloric effect and leads into mechanisms of decreasing or increasing dipolar entropy under applied electric field. Nevertheless, the mechanism...

[Phys. Rev. B 97, 094113] Published Wed Mar 28, 2018

]]>The paper investigates the role of spin-orbit interaction in the prediction of structural stability, lattice dynamics, elasticity, thermodynamic and transport properties (electrical resistivity and thermal conductivity) of lead under pressure with the FP-LMTO (full-potential linear-muffin-tin orbita...

[Phys. Rev. B 97, 094114] Published Wed Mar 28, 2018

]]>Results from hybrid density functional theory calculations on the thermodynamic stability and optical properties of the Zn vacancy $\left({V}_{\text{Zn}}\right)$ complexed with common donor impurities in ZnO are reported. Complexing ${V}_{\text{Zn}}$ with donors successively removes its charge-state transition levels in the band gap, sta...

[Phys. Rev. B 97, 104109] Published Tue Mar 27, 2018

]]>Most of the group IV, III-V, and II-VI compounds crystallize in semiconductor structures under ambient conditions. Upon application of pressure, they undergo structural phase transitions to more closely packed structures, sometimes metallic phases. We have performed density functional calculations u...

[Phys. Rev. B 97, 094111] Published Mon Mar 26, 2018

]]>Binary borides has been a subject of extensive research. However, the exact compositions and crystal structures of sodium borides remained controversial. Here, using the *ab initio* variable-composition evolutionary algorithm, a new stable ${\mathrm{Na}}_{2}{\mathrm{B}}_{30}$ with $I{2}_{1}{2}_{1}{2}_{1}$ symmetry ($I{2}_{1}{2}_{1}{2}_{1}-{\mathrm{Na}}_{2}{\mathrm{B}}_{30}$) is found, which ...

[Phys. Rev. B 97, 100102(R)] Published Mon Mar 26, 2018

]]>We study finite-temperature dynamical quantum phase transitions (DQPTs) by means of the fidelity and the interferometric Loschmidt echo (LE) induced metrics. We analyze the associated dynamical susceptibilities (Riemannian metrics), and derive analytic expressions for the case of two-band Hamiltonia...

[Phys. Rev. B 97, 094110] Published Fri Mar 23, 2018

]]>Ferroelectrics have long been recognized as one of the candidate class of materials for applications in photovoltaic devices. Recently, ferroelectric perovskite $(\text{K},\text{Ba})(\text{Ni},\text{Nb}){\mathrm{O}}_{3-\delta}$ has been successfully synthesized and demonstrated to have a near-optimal band gap (1.39 eV), exhibiting good photovoltai...

[Phys. Rev. B 97, 094109] Published Thu Mar 22, 2018

]]>The freezing temperature of solid hydrogen may be significantly lowered below its bulk value by encapsulating the sample in a restricted geometry. The authors report on an electron-spin resonance (ESR) study of H atoms, stabilized in highly porous solid mixtures of neon and molecular hydrogen at temperatures below 1 K. The ESR analysis shows that H atoms stabilize into two different substitutional sites of the Ne lattice and into H${}_{2}$ clusters, formed in solid neon. The hydrogen atoms in H${}_{2}$ clusters rapidly recombine upon raising the temperature from 0.1 to 0.3–0.6 K, which is attributed to a solid-liquid transition in the H${}_{2}$ clusters formed in solid Ne.

[Phys. Rev. B 97, 104108] Published Wed Mar 21, 2018

]]>Modeling the behavior of materials composed of elements with different bonding and electronic structure character for large spatial and temporal scales and over a large compositional range is a challenging problem. Cases in point are amorphous alloys of Si, a prototypical covalent material, and Li, ...

[Phys. Rev. B 97, 094106] Published Tue Mar 20, 2018

]]>In a ferroelectric field effect transistor (FeFET), it is generally assumed that the ferroelectric gate plays a purely electrostatic role. Recently it has been shown that in some cases, which could be called “active FeFETs,” electronic states in the ferroelectric contribute to the device conductance...

[Phys. Rev. B 97, 094107] Published Tue Mar 20, 2018

]]>We demonstrate midinfrared second-harmonic generation as a highly sensitive phonon spectroscopy technique that we exemplify using $\alpha $-quartz (${\mathrm{SiO}}_{2}$) as a model system. A midinfrared free-electron laser provides direct access to optical phonon resonances ranging from 350 to $1400\phantom{\rule{4pt}{0ex}}{\mathrm{cm}}^{-1}$. While the extremely...

[Phys. Rev. B 97, 094108] Published Tue Mar 20, 2018

]]>We show that a single ring resonator undergoing dynamic modulation can be used to create a synthetic space with an arbitrary dimension. In such a system, the phases of the modulation can be used to create a photonic gauge potential in high dimensions. As an illustration of the implication of this co...

[Phys. Rev. B 97, 104105] Published Mon Mar 19, 2018

]]>Understanding and quantifying the strength or elastic limit of diamond single crystals is of considerable scientific and technological importance, and has been a subject of long standing theoretical and experimental interest. To examine the effect of crystalline anisotropy on strength and deformatio...

[Phys. Rev. B 97, 104106] Published Mon Mar 19, 2018

]]>The nature of the nematic state in FeSe remains one of the major unsolved mysteries in Fe-based superconductors. Both spin and orbital physics have been invoked to explain the origin of this phase. Here we present experimental evidence for frustrated, short-range magnetic order, as suggested by seve...

[Phys. Rev. B 97, 104107] Published Mon Mar 19, 2018

]]>Friction between sliding objects is a phenomenon so ubiquitous that it is easily forgotten how few of its microscopic details are properly understood. To gain new insight into the dynamical mechanism of sliding dissipation, the authors investigate a minimal model of a rigid slider traveling over a harmonic substrate. With the analytical tools of linear response theory, the authors obtain an expression for the dynamical friction that depends on known static physical quantities. This result sheds new light on the physical intertwining between dissipation and the phononic degrees of freedom of the substrate.

[Phys. Rev. B 97, 104104] Published Thu Mar 15, 2018

]]>Raman spectroscopy is employed to probe directly the soft rotation and tilting modes, which are two primary order parameters predicted in the hybrid improper ferroelectric material ${\mathrm{Ca}}_{3}{\mathrm{Mn}}_{2}{\mathrm{O}}_{7}$. We observe a giant softening of the $107-{\mathrm{cm}}^{-1}$ octahedron tilting mode by $26\phantom{\rule{0.28em}{0ex}}{\mathrm{cm}}^{-1}$ on heating through the structu...

[Phys. Rev. B 97, 094104] Published Wed Mar 14, 2018

]]>A series of iron arsenides (e.g., ${\text{CaRbFe}}_{4}{\text{As}}_{4},{\text{SrCsFe}}_{4}{\text{As}}_{4}$) have been discovered recently, and have provoked a rise in superconductor searches in a different phase, known as the 1144 phase. For the presence of various chemical substitutions, it is believed that more 1144 compounds remain to be discove...

[Phys. Rev. B 97, 094105] Published Wed Mar 14, 2018

]]>To verify the first-order liquid-liquid transition (LLT) in liquid Cs reported by Falconi *et al.* [Phys. Rev. Lett. **94**, 125507 (2005).], the pressure dependence of liquid density was measured up to 5 GPa by an x-ray absorption method. The results showed that the density continuously increases over th...

[Phys. Rev. B 97, 100101(R)] Published Wed Mar 14, 2018

]]>It is well known that plastic deformation is a highly nonlinear dissipative irreversible phenomenon of considerable complexity. As a consequence, little progress has been made in modeling some well-known size-dependent properties of plastic deformation, for instance, calculating hardness as a functi...

[Phys. Rev. B 97, 104103] Published Mon Mar 12, 2018

]]>Laser-heated diamond-anvil cell (LHDAC) experiments reveal electronic changes in KBr at pressures between $\sim 13\u201381\phantom{\rule{0.28em}{0ex}}\mathrm{GPa}$ when heated to high temperatures that cause runaway heating to temperatures in excess of $\sim 5000\phantom{\rule{0.28em}{0ex}}\mathrm{K}$. The drastic changes in absorption behavior of KBr are interpreted as rapid formation of...

[Phys. Rev. B 97, 094103] Published Fri Mar 09, 2018

]]>*Ab initio* density-functional calculations are used to investigate the response of four face-centered-cubic (fcc) high-entropy alloys (HEAs) to tensile and shear loading. The ideal tensile and shear strengths (ITS and ISS) of the HEAs are studied by employing first-principles alloy theory formulated ...

[Phys. Rev. B 97, 094102] Published Wed Mar 07, 2018

]]>Helium bubbles can form in a wide variety of materials and are of significance in a great variety of circumstances, ranging from electronics through nuclear physics or geology to outer-space exploration. However, their properties remain elusive, especially at the nanometer scale. Here, the authors study by means of transmission electron microscopy the structural modification and, simultaneously, the helium emission from individual nanosized bubbles in silicon during $i\phantom{\rule{0}{0ex}}n\phantom{\rule{0.333em}{0ex}}s\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}t\phantom{\rule{0}{0ex}}u$ annealing. It is shown that, surprisingly, helium emission takes place at temperatures where bubble migration has barely begun. Analytical modeling of helium emission suggests that helium is in its solid state in the most highly pressurized bubbles.

[Phys. Rev. B 97, 104102] Published Wed Mar 07, 2018

]]>We report an observation of a phase transition in ${\mathrm{Ce}}_{3}{\mathrm{Rh}}_{4}{\mathrm{Sn}}_{13}$ with the transition temperature ${T}^{*}\simeq 350$ K by means of synchrotron x-ray powder diffraction, specific heat, electrical resistivity, Seebeck coefficient, thermal conductivity, as well as ${}^{119}\mathrm{Sn}$ nuclear magnetic resonance (NMR) measurements. Th...

[Phys. Rev. B 97, 094101] Published Tue Mar 06, 2018

]]>Solving the phase problem in x-ray crystallography has occupied a considerable scientific effort in the 20th century and led to great advances in structural science. Here we use x-ray ptychography to demonstrate an interference method which measures the phase of the beam transmitted through a crysta...

[Phys. Rev. B 97, 104101] Published Tue Mar 06, 2018

]]>Landau free-energy expansion parameters for $0.64\mathrm{Pb}\left(\mathrm{M}{\mathrm{g}}_{1/3}\mathrm{N}{\mathrm{b}}_{2/3}\right){\mathrm{O}}_{3}-0.36\mathrm{PbTi}{\mathrm{O}}_{3}$ single crystal were determined from the temperature-dependent polarization-electric field ($P-E$) hysteresis loops along ${\left[001\right]}_{C}$, the temperature-dependent dielectric constant ${\varepsilon}_{11}$, and the electric-field-induced tetragonal-rhom...

[Phys. Rev. B 97, 054114] Published Wed Feb 28, 2018

]]>Materials that are simultaneously transparent and electrically conductive play a key role in optoelectronic devices. Barium stannate has recently come to the forefront as a promising new transparent conductor, but its conductivity has been difficult to control. The authors have performed computational studies to determine the mechanisms that limit doping. They find that atomic-scale defects, such as vacancies in the crystal lattice, are responsible, but their formation can be controlled by tailoring the growth conditions. The authors also investigated related materials, such as strontium stannate and calcium stannate, which are transparent even in the ultraviolet. Calcium stannate is found to always be insulating, but guidelines are provided for maximizing the conductivity of the strontium compound.

[Phys. Rev. B 97, 054112] Published Mon Feb 26, 2018

]]>A phase-field model of a crystalline material is introduced to develop the necessary theoretical framework to study plastic flow due to dislocation motion. We first obtain the elastic stress from the phase-field crystal free energy under weak distortion and show that it obeys the stress-strain relat...

[Phys. Rev. B 97, 054113] Published Mon Feb 26, 2018

]]>The chemical reaction products of molecular hydrogen $\left({\mathrm{H}}_{2}\right)$ with selenium (Se) are studied by synchrotron x-ray diffraction (XRD) and Raman spectroscopy at high pressures. We find that a common ${\mathrm{H}}_{2}\mathrm{Se}$ is synthesized at 0.3 GPa using laser heating. Upon compression at 300 K, a crystal of the theoreticall...

[Phys. Rev. B 97, 064107] Published Mon Feb 26, 2018

]]>The magnetopolaron effect on shallow-impurity states in semiconductors is investigated when subjected simultaneously to a magnetic field and an intense terahertz laser field within the Faraday configuration. We use a time-dependent nonperturbative theory to describe electron interactions. The extern...

[Phys. Rev. B 97, 064108] Published Mon Feb 26, 2018

]]>The number of paramagnetic materials that undergo a structural phase transition is rather small, which can perhaps explain the limited understanding of the band Jahn-Teller mechanism responsible for this effect. Here we present a structural phase transition observed in paramagnetic ${\mathrm{Y}}_{2}\mathrm{In}$ at temperatu...

[Phys. Rev. B 97, 054111] Published Fri Feb 23, 2018

]]>Granular crystals are periodic structures of elastic beads arranged in crystal lattices. One important feature of granular crystals is that the interactions between beads can take place via noncentral contact forces, leading to the propagation of rotational and coupled rotational-translational waves...

[Phys. Rev. B 97, 060101(R)] Published Thu Feb 22, 2018

]]>Using first-principles calculations, we systematically study the elastic stiffness constants, mechanical properties, elastic wave velocities, Debye temperature, melting temperature, and specific heat of several thermodynamically stable crystal structures of ${\mathrm{Bi}}_{x}{\mathrm{Sb}}_{1-x}$ ($0<x<1$) binaries, which are...

[Phys. Rev. B 97, 054108] Published Tue Feb 20, 2018

]]>Tin titanate ($\mathrm{SnTi}{\mathrm{O}}_{3}$) has been notoriously impossible to prepare as a thin-film ferroelectric, probably because high-temperature annealing converts much of the $\mathrm{S}{\mathrm{n}}^{2+}$ to $\mathrm{S}{\mathrm{n}}^{4+}$. In the present paper, we show two things: first, perovskite phase $\mathrm{SnTi}{\mathrm{O}}_{3}$ can be prepared by atomic-layer deposition directly o...

[Phys. Rev. B 97, 054109] Published Tue Feb 20, 2018

]]>Ferroelectric materials are characterized by a spontaneous polar distortion. The behavior of such distortion in the presence of free charge is the key to the physics of metallized ferroelectrics in particular, and of structurally polar metals more generally. Using first-principles simulations, here ...

[Phys. Rev. B 97, 054107] Published Thu Feb 15, 2018

]]>$(\mathrm{Mg},\mathrm{Fe})\mathrm{Si}{\mathrm{O}}_{3}$ perovskite is the most abundant mineral of the Earth's lower mantle, and compounds with the perovskite structure are perhaps the most widely employed ceramics. Hence, they attract both geophysicists and material scientists. Several investigations attempted to predict their structural evo...

[Phys. Rev. B 97, 064106] Published Wed Feb 14, 2018

]]>We report an experimental and numerical study of femtosecond multipulse laser-induced densification in vitreous silica ($v-{\mathrm{SiO}}_{2}$) and its signature in Raman spectra. We compare the experimental findings to the recently developed molecular dynamics (MD) approach accounting for bond breaking due to lase...

[Phys. Rev. B 97, 054106] Published Tue Feb 13, 2018

]]>The *thermal lines* method for the evaluation of vibrational expectation values of electronic observables [B. Monserrat, Phys. Rev. B **93**, 014302 (2016)] was recently proposed as a physically motivated approximation offering balance between the accuracy of direct Monte Carlo integration and the low com...

[Phys. Rev. B 97, 054104] Published Mon Feb 12, 2018

]]>A hyperuniform many-body system is characterized by a structure factor $S\left(\mathit{k}\right)$ that vanishes in the small-wave-number limit or equivalently by a local number variance ${\sigma}_{N}^{2}\left(R\right)$ associated with a spherical window of radius $R$ that grows more slowly than ${R}^{d}$ in the large-$R$ limit. Thus, the hyperuniformity implies...

[Phys. Rev. B 97, 054105] Published Mon Feb 12, 2018

]]>Ferroelectric-ferromagnetic multiferroic composites are of great interest both from the scientific and technological standpoints. The extent of coupling between polarization and magnetization in such two-phase systems depends on how efficiently the magnetostrictive and electrostrictive/piezoelectric...

[Phys. Rev. B 97, 064103] Published Mon Feb 12, 2018

]]>With increasing temperature, metallic glasses (MGs) undergo first glass transition without pronounced structural change and then crystallization with distinct variation in structure and properties. The present study shows a structural change of short-range order induced by an electron-delocalization...

[Phys. Rev. B 97, 064104] Published Mon Feb 12, 2018

]]>We introduce a local order metric (LOM) that measures the degree of order in the neighborhood of an atomic or molecular site in a condensed medium. The LOM maximizes the overlap between the spatial distribution of sites belonging to that neighborhood and the corresponding distribution in a suitable ...

[Phys. Rev. B 97, 064105] Published Mon Feb 12, 2018

]]>Defect formation in LiF, which is used as an observation window in ramp and shock experiments, has significant effects on its transmission properties. Given the extreme conditions of the experiments it is hard to measure the change in transmission directly. Using molecular dynamics, we estimate the ...

[Phys. Rev. B 97, 054103] Published Thu Feb 08, 2018

]]>The Gibbs free energy is the fundamental thermodynamic potential underlying the relative stability of different states of matter under constant-pressure conditions. However, computing this quantity from atomic-scale simulations is far from trivial, so the potential energy of a system is often used a...

[Phys. Rev. B 97, 054102] Published Tue Feb 06, 2018

]]>We report high-pressure Raman, synchrotron x-ray diffraction, and electrical transport studies on Weyl semimetals NbP and TaP along with first-principles density functional theoretical (DFT) analysis. The frequencies of first-order Raman modes of NbP harden with increasing pressure and exhibit a slo...

[Phys. Rev. B 97, 064102] Published Mon Feb 05, 2018

]]>The $\mathrm{Cu}\phantom{\rule{0.16em}{0ex}}\mathrm{\Sigma}5$ grain boundary (GB) fracture process has been simulated by the first-principles computational tensile test. An additional metastable state has been discovered during tensile tests. The energy of ideal mirror-symmetric GBs continuously changes with tensile strains. However, at high strains, ...

[Phys. Rev. B 97, 054101] Published Fri Feb 02, 2018

]]>Key properties of nine possible defect sites in hexagonal boron nitride (h-BN), ${V}_{\mathrm{N}},{{V}_{\mathrm{N}}}^{-1},{\mathrm{C}}_{\mathrm{N}},{V}_{\mathrm{N}}{\mathrm{O}}_{2\mathrm{B}},{V}_{\mathrm{N}}{\mathrm{N}}_{\mathrm{B}},{V}_{\mathrm{N}}{\mathrm{C}}_{\mathrm{B}},{V}_{\mathrm{B}}{C}_{\mathrm{N}},{V}_{\mathrm{B}}{\mathrm{C}}_{\mathrm{N}}\mathrm{S}{\mathrm{i}}_{\mathrm{N}}$, and ${V}_{\mathrm{N}}{\mathrm{C}}_{\mathrm{B}}\mathrm{S}{\mathrm{i}}_{\mathrm{B}}$, are predicted using density-functional theory and are corrected by applying results from high-level *ab initio* calculations. Observed h-BN electron-paramagnetic resona...

[Phys. Rev. B 97, 064101] Published Thu Feb 01, 2018

]]>Single-crystal x-ray diffraction studies with synchrotron radiation on the honeycomb iridate $\alpha -{\mathrm{Li}}_{2}{\mathrm{IrO}}_{3}$ reveal a pressure-induced structural phase transition with symmetry lowering from monoclinic to triclinic at a critical pressure of ${P}_{c}=3.8$ GPa. According to the evolution of the lattice parameters ...

[Phys. Rev. B 97, 020104(R)] Published Wed Jan 31, 2018

]]>