A systematic *ab initio* study of the influence of local magnetism on the generalized stacking fault energy (GSFE) surface in pure *fcc* iron at 0 K has been performed. In the calculations we considered ferro- and antiferro- (single- and double-layer) magnetic order of local moments as well as their com…

[Phys. Rev. B 93, 214115] Published Wed Jun 29, 2016

]]>We combine the ideas of intensity interferometry, polarization optics, and Bell's measurement into an experimental proposal which is hosted in a $\nu =2$ quantum Hall (QH) edge state. Our interferometer comprises of a single gate, that separates the spin-resolved edge states of $\nu =2$ state. An analog of wa…

[Phys. Rev. B 93, 220101(R)] Published Wed Jun 29, 2016

]]>Pressure-dependent powder x-ray diffraction, Raman spectroscopy, and dielectric constant measurements are performed on 0.$65{\mathrm{BiFeO}}_{3}\text{\u2212}0.35{\mathrm{PbTiO}}_{3}$. Four structural transitions are reported in 0–34 GPa range. The transitions are observed at 0.7(1), 0.8(1), 3.4(1), and 6.1(1) GPa, where the system transform…

[Phys. Rev. B 93, 214114] Published Tue Jun 28, 2016

]]>In recent years, material-induced noise arising from defects has emerged as an impediment to quantum-limited measurement in systems ranging from microwave qubits to gravity-wave interferometers. As experimental systems push to ever smaller dimensions, extrinsic system properties can affect its inter…

[Phys. Rev. B 93, 224110] Published Tue Jun 28, 2016

]]>Many grain boundaries (GBs) in crystalline materials develop highly disordered, liquidlike structures at high temperatures. In alloys, this premelting effect can be fueled by solute segregation and can occur at lower temperatures than in single-component systems. A premelted GB can be modeled by a t…

[Phys. Rev. B 93, 224108] Published Mon Jun 27, 2016

]]>Pressure-induced transitions from ordered intermetallic phases to substitutional alloys to semi-ordered phases were studied in a series of bismuth tellurides. By using angle-dispersive x-ray diffraction, the compounds ${\mathrm{Bi}}_{4}{\mathrm{Te}}_{5}$, BiTe, and ${\mathrm{Bi}}_{2}\mathrm{Te}$ were observed to form alloys with the disordered body-cent…

[Phys. Rev. B 93, 224109] Published Mon Jun 27, 2016

]]>Strained ${\mathrm{NaNbO}}_{3}$ films of different thicknesses are epitaxially grown on (110) ${\mathrm{NdGaO}}_{3}$ substrates. A detailed analysis of the permittivity of these films demonstrates that strain not only leads to a modification of the permittivity and the ferroelectric transition temperature, it also results in a pro…

[Phys. Rev. B 93, 224107] Published Wed Jun 22, 2016

]]>We explore the reactivity of xenon with sulfur under high pressure, using unbiased structure searching techniques combined with first-principles calculations, which identify a stable ${\mathrm{XeS}}_{2}$ compound crystallized in a Laves phase with hypercoordinated (16-fold) Xe at 191 GPa and 0 K. Taking the thermal…

[Phys. Rev. B 93, 214112] Published Tue Jun 21, 2016

]]>We report on a drastic change of the Ni collective magnetization dynamics when incorporated into a $\mathrm{Ni}\text{/}{\mathrm{V}}_{2}{\mathrm{O}}_{3}$ heterostructure. Two, unexpected, well-defined Ni ferromagnetic resonance (FMR) modes are observed in the coexistence region of the first-order ${\mathrm{V}}_{2}{\mathrm{O}}_{3}$ structural phase transition (SPT). The phase…

[Phys. Rev. B 93, 214113] Published Tue Jun 21, 2016

]]>The effect of composition on the antiphase boundary (APB) energy of Ni-based $\mathrm{L}{1}_{2}$-ordered alloys is investigated by *ab initio* calculations employing the coherent potential approximation. The calculated APB energies for the {111} and {001} planes reproduce experimental values of the APB energy. The AP…

[Phys. Rev. B 93, 224106] Published Mon Jun 20, 2016

]]>Understanding the spontaneous emergence of dislocation patterns during plastic deformation is a long standing challenge in dislocation theory. During the past decades several phenomenological continuum models of dislocation patterning were proposed, but few of them (if any) are derived from microsco…

[Phys. Rev. B 93, 214110] Published Fri Jun 17, 2016

]]>Because of the enormous range of time and space scales involved in dislocation dynamics, plastic modeling at macroscale requires a continuous formulation. In this paper, we present a rigorous formulation of the transition between the discrete, where plastic flow is resolved at the scale of individua…

[Phys. Rev. B 93, 214111] Published Fri Jun 17, 2016

]]>We present first-principles calculations of the vibrational properties of the transition-metal dichalcogenide $1T\text{\u2212}{\mathrm{TaS}}_{2}$ for various thicknesses in the high-temperature (undistorted) phase and the low-temperature commensurate charge density wave (CDW) phase. We also present measurements of the Raman sp…

[Phys. Rev. B 93, 214109] Published Thu Jun 16, 2016

]]>The phase diagram of the Be-H system is measured up to 100 GPa. ${\mathrm{BeH}}_{2}$ is the only stoichiometry observed. Three crystalline phases are identified using synchrotron x-ray diffraction. The $Ibam$ structure, already known at ambient pressure, is stable up to 27 GPa. The $P{4}_{1}{2}_{1}2$ structure, isotypical to the…

[Phys. Rev. B 93, 224104] Published Wed Jun 15, 2016

]]>Glassy freezing dynamics was investigated in ${\mathrm{BaZr}}_{0.5}{\mathrm{Ti}}_{0.5}{\mathrm{O}}_{3}$ (BZT50) ceramic samples by means of dielectric spectroscopy in the frequency range 0.001 Hz–1 MHz at temperatures $10<T<300$ K. From measurements of the quasistatic dielectric polarization in bias electric fields up to $\sim 28$ kV/cm it has …

[Phys. Rev. B 93, 224105] Published Wed Jun 15, 2016

]]>We derived and thoroughly tested a bond-order potential (BOP) for body-centered-cubic (bcc) magnetic iron that can be employed in atomistic calculations of a broad variety of crystal defects that control structural, mechanical, and thermodynamic properties of this technologically important metal. Th…

[Phys. Rev. B 93, 214107] Published Tue Jun 14, 2016

]]>In this article, we investigate the kinetics of the iron $\alpha -\varepsilon $ transition under laser-driven ramp compression for deformation rates ranging from 3 to $9\times {10}^{7}\phantom{\rule{0.28em}{0ex}}{\mathrm{s}}^{-1}$. As in previous work, we observe a plateau in the rear surface velocity profile at the transition. With increasing deformation rate the transit…

[Phys. Rev. B 93, 214108] Published Tue Jun 14, 2016

]]>The low-temperature softening of the TO1 phonon of ${\mathrm{SrTiO}}_{3}$ (STO), which determines its incipient ferroelectricity, is known to be partially hindered either in the bulk under strong electric fields, or in thin STO films. Here we show, by terahertz (THz) reflectivity measurements, that a similar effect…

[Phys. Rev. B 93, 224103] Published Tue Jun 14, 2016

]]>By means of first-principles calculations for the SbSI semiconductor, we show that bare density functional theory fails to reproduce the experimentally observed ferroelectric phase, whereas a more advanced approach, based on hybrid functionals, correctly works. When comparing the paraelectric and fe…

[Phys. Rev. B 93, 214106] Published Fri Jun 10, 2016

]]>Motivated by recent developments in nitrogen-rich transition-metal nitrides, the stability of chromium mononitride (CrN) and the possible formation of chromium dinitride $\left(\mathrm{Cr}{\mathrm{N}}_{2}\right)$ are studied using density functional theory (with the Perdew-Burke-Ernzerhof functional within the generalized gradient app…

[Phys. Rev. B 93, 214104] Published Wed Jun 08, 2016

]]>We investigate nonlinear elastic deformations in the phase field crystal model and derived amplitude equation formulations. Two sources of nonlinearity are found, one of them is based on geometric nonlinearity expressed through a finite strain tensor. This strain tensor is based on the inverse right…

[Phys. Rev. B 93, 214105] Published Wed Jun 08, 2016

]]>In-plane heterostructures of two-dimensional (2D) materials form interface misfit dislocations to relieve lattice mismatch strain, much like heterostructures of 3D materials. Here, using graphene-hexagonal boron nitride (h-BN) as a model system, we consider interface misfit dislocations in 2D latera…

[Phys. Rev. B 93, 214103] Published Mon Jun 06, 2016

]]>Metal atom wires represent an important class of nanomaterials in the development of future electronic devices and other functional applications. Using first-principles calculations within density functional theory, we carry out a systematic study of the quantum stability of freestanding atom wires …

[Phys. Rev. B 93, 224102] Published Mon Jun 06, 2016

]]>We extend the self-consistent mean field (SCMF) method to the calculation of the Onsager matrix of Fe-based interstitial solid solutions. Both interstitial jumps and substitutional atom-vacancy exchanges are accounted for. A general procedure is introduced to split the Onsager matrix of a dilute sol…

[Phys. Rev. B 93, 224101] Published Fri Jun 03, 2016

]]>Scandium fluoride (${\mathrm{ScF}}_{3}$), having cubic ${\mathrm{ReO}}_{3}$-type structure, has attracted much scientific attention due to its rather strong negative thermal expansion (NTE) in the broad temperature range from 10 to 1100 K. Here we use the results of diffraction and extended x-ray absorption fine-structure (EXAFS) …

[Phys. Rev. B 93, 214101] Published Thu Jun 02, 2016

]]>Motivated by understanding the emergence of thermodynamic restoring forces and oscillations, we develop a quantum-mechanical model of a bath of spins coupled to the elasticity of a material. We show our model reproduces the behavior of a variety of entropic springs while enabling investigation of no…

[Phys. Rev. B 93, 214102] Published Thu Jun 02, 2016

]]>We study the structural evolution of ${\mathrm{Sr}}_{3}{\mathrm{Ir}}_{2}{\mathrm{O}}_{7}$ as a function of pressure using x-ray diffraction. At a pressure of 54 GPa at room temperature, we observe a first-order structural phase transition, associated with a change from tetragonal to monoclinic symmetry and accompanied by a 4% volume collapse.…

[Phys. Rev. B 93, 174118] Published Tue May 31, 2016

]]>$\mathrm{LaOBi}{\mathrm{S}}_{2}$-type materials have drawn much attention recently because of various interesting physical properties, such as low-temperature superconductivity, hidden spin polarization, and electrically tunable Dirac cones. However, it was generally assumed that each $\mathrm{LaOBi}{\mathrm{S}}_{2}$-type compound has a unique and …

[Phys. Rev. B 93, 174119] Published Tue May 31, 2016

]]>Ferroelectrics form domain patterns that minimize their energy subject to imposed boundary conditions. In a linear, constrained theory, that neglects domain-wall energy, periodic domain patterns in the form of multirank laminates can be identified as minimum-energy states. However, when these lamina…

[Phys. Rev. B 93, 174120] Published Tue May 31, 2016

]]>We present a structural analysis of the substituted system $({\mathrm{Ba}}_{1-x}{\mathrm{Sr}}_{x}){\mathrm{CuSi}}_{2}{\mathrm{O}}_{6}$, which reveals a stable tetragonal crystal structure down to 1.5 K. We explore the structural details with low-temperature neutron and synchrotron powder diffraction, room-temperature, and cryogenic high-resolution NMR, as …

[Phys. Rev. B 93, 174121] Published Tue May 31, 2016

]]>Samarium orthoferrite $\left(\mathrm{SmFe}{\mathrm{O}}_{3}\right)$ has been the subject of debate on the existence or nonexistence of ferroelectric properties. It has a high spin-reorientation transition temperature ${T}_{\mathrm{SR}}$ (480 K). Detailed synchrotron x-ray diffraction and Raman spectroscopy dielectric investigations in the 300 to 600 K…

[Phys. Rev. B 93, 174117] Published Thu May 26, 2016

]]>We probe here the optical relaxation properties of Mg-doped wide-band-gap ${\mathrm{LiNbO}}_{3}$ single crystals with both a high spectral and temporal resolution at cryogenic temperatures. Surprisingly, we observe the photoluminescence to decay in a two-step process: a fast relaxation and a slower one centered aro…

[Phys. Rev. B 93, 174116] Published Wed May 25, 2016

]]>We report the structural changes of three $\mathrm{YF}{\mathrm{e}}_{2}{\mathrm{O}}_{4-\delta}$ ($\delta <0.1$) specimens using high resolution synchrotron x-ray powder diffraction between 80 and 300 K. All samples adopt a rhombohedral cell at room temperature (space group $R\overline{3}m$). This cell becomes unstable for the three samples on cooling, and the …

[Phys. Rev. B 93, 184110] Published Wed May 25, 2016

]]>Electric fields are known to favor long-range polar order through the aligning of electric dipoles in relation to Coulomb's force. Therefore, it would be surprising to observe a disordered polar state induced from an ordered state by electric fields. Here we show such an unusual phenomenon in a poly…

[Phys. Rev. B 93, 174114] Published Tue May 24, 2016

]]>Local distortions of the ideal periodic structure in crystals around impurity atoms play an important role in various physical properties of materials. The aim of this study was to investigate the static distortions around cadmium impurity atoms in a ${\text{SnCd}}_{0.0026}$ single crystal using atomic resolution…

[Phys. Rev. B 93, 174115] Published Tue May 24, 2016

]]>A metallic state enabled by the metal-insulator transition (MIT) in single crystal $\mathrm{V}{\mathrm{O}}_{2}\left(\mathrm{A}\right)$ nanorods is demonstrated, which provides important physical foundation in experimental understanding of MIT in $\mathrm{V}{\mathrm{O}}_{2}$. The observed tetragonal metallic state at ∼28 GPa should be interpreted as a distinct metastab…

[Phys. Rev. B 93, 184109] Published Tue May 24, 2016

]]>Accurate theoretical calculations of the nonlinear elastic response of strong solids (e.g., diamond) constitute a fundamental and important scientific need for understanding the response of such materials and for exploring the potential synthesis and design of novel solids. However, without correspo…

[Phys. Rev. B 93, 174113] Published Mon May 23, 2016

]]>Variation of the phase of the beam transmitted through a crystalline material as a function of the rocking angle is a well-known dynamical effect in x-ray scattering. Unfortunately, it is not so easy to directly measure these phase variations in a conventional scattering experiment. It was recently …

[Phys. Rev. B 93, 184107] Published Mon May 23, 2016

]]>A correct description of hydrogen diffusion and trapping is the prerequisite for an understanding of the phenomenon of hydrogen embrittlement. In this study, we carried out extensive first-principles calculations based on density functional theory to investigate the interaction of H with TiC precipi…

[Phys. Rev. B 93, 184108] Published Mon May 23, 2016

]]>The metal-insulator switching characteristics of ${\mathrm{VO}}_{2}$ play a crucial role in the performances of ${\mathrm{VO}}_{2}$-based devices. In this paper we study high-quality (010)-oriented epitaxial films grown on (001) sapphire substrates by means of electron-beam evaporation and investigate the role of interface defects…

[Phys. Rev. B 93, 184106] Published Fri May 20, 2016

]]>The traditional derivation of the elastic anomalies associated with ferroelectric (FE) phase transitions in the framework of the Landau theory is combined with the piezoelectric constitutive relations instead of being explicitly carried out with a definite expression of the FE part of the free energ…

[Phys. Rev. B 93, 174111] Published Thu May 19, 2016

]]>The structural and mechanical properties of N-doped graphene (NG) are investigated using reactive force field (ReaxFF) potentials in large-scale molecular dynamics simulations. We found that ripples, which are induced by the dopants, change the roughness of NG, which depends on the number of dopants…

[Phys. Rev. B 93, 174112] Published Thu May 19, 2016

]]>Bragg coherent x-ray diffractive imaging is a powerful technique for investigating dynamic nanoscale processes in nanoparticles immersed in reactive, realistic environments. Its temporal resolution is limited, however, by the oversampling requirements of three-dimensional phase retrieval. Here, we s…

[Phys. Rev. B 93, 184105] Published Thu May 19, 2016

]]>The mechanical properties and electronic structure of polymorphic tungsten carbides with different stacking sequences have been investigated by means of density functional theory. The stacking sequence strongly influences the stability and mechanical strength of these polymorphs. Using the plastic p…

[Phys. Rev. B 93, 184104] Published Wed May 18, 2016

]]>We report a density-functional study on the evolution of the electronic and lattice structure in ${\mathrm{BiFeO}}_{3}$ with injected electrons and holes. First, the self-trapping of electrons and holes was investigated. We found that the injected electrons tend to be localized on Fe sites due to the local lattice …

[Phys. Rev. B 93, 174110] Published Tue May 17, 2016

]]>The atomic and electronic structures of ${60}^{\circ}$ glide perfect and ${30}^{\circ}/{90}^{\circ}$ glide partial dislocations in CdTe are studied using combined semi-empirical and density functional theory calculations. The calculations predict that the dislocation cores tend to undergo significant reconstructions along the dis…

[Phys. Rev. B 93, 174109] Published Mon May 16, 2016

]]>The role of oxygen doping in CdTe is addressed by first-principles calculations. Formation energies, charge transition levels, and quasiparticle defect states are calculated within the $\text{DFT}+GW$ formalism. The formation of a new defect is identified, the $\left({\text{O}}_{\text{Te}}{\text{-Te}}_{\text{Cd}}\right)$ complex. This complex is energeticall…

[Phys. Rev. B 93, 184103] Published Mon May 16, 2016

]]>We extend the nested sampling algorithm to simulate materials under periodic boundary and constant pressure conditions, and show how it can be used to determine the complete equilibrium phase diagram for a given potential energy function, efficiently and in a highly automated fashion. The only input…

[Phys. Rev. B 93, 174108] Published Fri May 13, 2016

]]>Using first-principles calculations based on density functional theory, we have studied the mechanical, electronic, and magnetic properties of Heusler alloys, namely, ${\mathrm{Ni}}_{2}BC$ and ${\mathrm{Co}}_{2}BC$ ($B$ = Sc, Ti, V, Cr, and Mn as well as Y, Zr, Nb, Mo, and Tc; $C$ = Ga and Sn). On the basis of electronic structure (de…

[Phys. Rev. B 93, 184102] Published Fri May 13, 2016

]]>To achieve a fundamental understanding of the multiferroic behavior and electronic properties of intrinsic vacancies in $\mathrm{BiFe}{\mathrm{O}}_{3}$, here we performed first-principles calculations based on hybrid Hartree-Fock density functional theories, which can accurately describe defect electronic structures. Oxygen…

[Phys. Rev. B 93, 174107] Published Thu May 12, 2016

]]>We propose a method to measure the hyperfine vectors between a nitrogen-vacancy (NV) center and an environment of interacting nuclear spins. Our protocol enables the generation of tunable electron-nuclear coupling Hamiltonians while suppressing unwanted internuclear interactions. In this manner, eac…

[Phys. Rev. B 93, 174104] Published Tue May 10, 2016

]]>Hydrogen sulfide $\left({\mathrm{H}}_{2}\mathrm{S}\right)$ was studied by x-ray synchrotron diffraction and Raman spectroscopy up to 150 GPa at 180–295 K and by quantum-mechanical variable-composition evolutionary simulations. The experiments show that ${\mathrm{H}}_{2}\mathrm{S}$ becomes unstable with respect to formation of compounds with different structur…

[Phys. Rev. B 93, 174105] Published Tue May 10, 2016

]]>Premelting or virtual melting was proposed previously as an important deformation mechanism for high strain-rate loading. However, two questions remain outstanding: how premelting occurs exactly, and whether it plays a role in plastic deformation independent of, parasitic on, or synergetic with, dis…

[Phys. Rev. B 93, 174106] Published Tue May 10, 2016

]]>Limit-periodic structures are well ordered but nonperiodic, and hence have nontrivial vibrational modes. We study a ball and spring model with a limit-periodic pattern of spring stiffnesses and identify a set of extended modes with arbitrarily low participation ratios, a situation that appears to be…

[Phys. Rev. B 93, 174102] Published Mon May 09, 2016

]]>Τhe magnetoelectric $\mathrm{ZnC}{\mathrm{r}}_{2}\mathrm{S}{\mathrm{e}}_{4}$ spinel, with space group $Fd\overline{3}m$, undergoes a reversible first-order structural transition initiating at 17 GPa, as revealed by our high-pressure x-ray diffraction studies at room temperature. We tentatively assign the high-pressure modification to an $A\mathrm{M}{\mathrm{o}}_{2}{\mathrm{S}}_{4}$-type phase, a …

[Phys. Rev. B 93, 174103] Published Mon May 09, 2016

]]>The origin of ferroelectric polarization in tetragonal tungsten-bronze- (TTB-) type oxide strontium barium niobate (SBN) is investigated using first-principles density functional calculations. We study in particular the relationship between the polarization and the cation and vacancy ordering on alk…

[Phys. Rev. B 93, 180101(R)] Published Mon May 09, 2016

]]>In a ferroelectric helimagnetic phase of a spin-driven multiferroic, ${\mathrm{CuFeO}}_{2}$, we find irreversibly additive evolution of electric polarization $P$ induced by sweeping magnetic field $H$ under an applied electric field $E$, despite a large coercive electric field in the phase. From the unpolarized neutron d…

[Phys. Rev. B 93, 174101] Published Tue May 03, 2016

]]>We demonstrate that the melting points and other thermodynamic quantities of the alkali metals can be calculated based on static crystalline properties. To do this we derive analytic interatomic potentials for the alkali metals fitted precisely to cohesive and vacancy energies, elastic moduli, the l…

[Phys. Rev. B 93, 184101] Published Mon May 02, 2016

]]>We introduce an algorithm for the reconstruction of the complex transmission function of a specimen using segmented detectors in scanning transmission electron microscopy geometry. The phase of the transmission function can be related to magnetic and electric fields within the specimen and is sensit…

[Phys. Rev. B 93, 134116] Published Wed Apr 27, 2016

]]>Oxygen vacancies in ${\mathrm{LaAlO}}_{3}$ (LAO) play an important role in the formation of the two-dimensional electron gas observed at the ${\mathrm{LaAlO}}_{3}\text{/}{\mathrm{SrTiO}}_{3}$ interface and affect the performance of MOSFETs using LAO as a gate dielectric. However, their spectroscopic properties are still poorly understood, which hamper…

[Phys. Rev. B 93, 134114] Published Mon Apr 25, 2016

]]>A formalism for the vacancy formation energies in random alloys within the single-site mean-filed approximation, where vacancy-vacancy interaction is neglected, is outlined. It is shown that the alloy configurational entropy can substantially reduce the concentration of vacancies at high temperature…

[Phys. Rev. B 93, 134115] Published Mon Apr 25, 2016

]]>Segregation-induced structural transitions in metallic grain boundaries are studied with hybrid atomistic Monte Carlo/molecular dynamics simulations using Cu-Zr as a model system, with a specific emphasis on understanding the effect of grain boundary character. With increasing global composition, th…

[Phys. Rev. B 93, 134113] Published Fri Apr 22, 2016

]]>The effect of external mechanical fields on relaxor $0.94\left(\mathrm{N}{\mathrm{a}}_{1/2}\mathrm{B}{\mathrm{i}}_{1/2}\right)\mathrm{Ti}{\mathrm{O}}_{3}\text{\u2212}0.06\mathrm{BaTi}{\mathrm{O}}_{3}$ was investigated by means of temperature- and stress-dependent dielectric constant measurements between 223 and 673 K. Analogous to previous investigations that showed an electric-field-induced ferroelectric long-ran…

[Phys. Rev. B 93, 134111] Published Wed Apr 20, 2016

]]>We studied the microscopic mechanism of the paraelectric-ferroelectric (PE-FE) phase transition of ${\mathrm{CsH}}_{2}{\mathrm{PO}}_{4}$ (CDP) by means of first-principles electronic structure calculations. The calculated structural parameters in the PE and FE phases as well as the total spontaneous polarization ${P}_{s}$ obtained with…

[Phys. Rev. B 93, 134112] Published Wed Apr 20, 2016

]]>High-resolution single crystal neutron diffraction measurements are presented probing the magnetostructural response to uniaxial pressure in the iron pnictide parent system ${\mathrm{BaFe}}_{2}{\mathrm{As}}_{2}$. Scattering data reveal a strain-activated, anisotropic broadening of nuclear Bragg reflections, which increase upon c…

[Phys. Rev. B 93, 144118] Published Wed Apr 20, 2016

]]>High-pressure solid-state transformations at high strain rates are usually observed after the fact, either during static holding or after unloading, or inferred from interferometry measurements of the sample surface. The emergence of femtosecond x-ray diffraction techniques provides insight into the…

[Phys. Rev. B 93, 144119] Published Wed Apr 20, 2016

]]>A complete structural solution of the bilayer iridate compound ${\mathrm{Sr}}_{3}{\mathrm{Ir}}_{2}{\mathrm{O}}_{7}$ presently remains outstanding. Previously reported structures for this compound vary and all fail to explain weak structural violations observed in neutron scattering measurements as well as the presence of a net ferromagnetic m…

[Phys. Rev. B 93, 134110] Published Tue Apr 19, 2016

]]>A new ground state of textbook compound strontium titanate $\left(\mathrm{SrTi}{\mathrm{O}}_{3}\right)$ is obtained by inducing a specific core-shell structure of the particles. Using a combination of high energy synchrotron and neutron diffraction, we demonstrate a lowering of the ferroelastic ground state towards a new antiferrodist…

[Phys. Rev. B 93, 144117] Published Tue Apr 19, 2016

]]>We investigated the structural phase transition of ${\mathrm{BaAl}}_{2}{\mathrm{O}}_{4}$, which has a network structure with corner-sharing ${\mathrm{AlO}}_{4}$ tetrahedra, via synchrotron x-ray thermal diffuse scattering measurements and first-principles calculations. ${\mathrm{BaAl}}_{2}{\mathrm{O}}_{4}$ shows the structural phase transition at ${T}_{\mathrm{C}}=451.4$ K from the $P{6}_{3}22$ p…

[Phys. Rev. B 93, 134108] Published Mon Apr 18, 2016

]]>The local structure of ${\mathrm{IrTe}}_{2}$ has been studied by iridium ${L}_{3}$-edge x-ray absorption spectroscopy (XAS) measurements as a function of pressure, performed at two temperatures (100 and 295 K) across the structural phase transition at $\sim 270$ K. Extended x-ray absorption fine structure (EXAFS) and x-ray abso…

[Phys. Rev. B 93, 134109] Published Mon Apr 18, 2016

]]>By means of circularly polarized x rays at the Dy ${L}_{3}$ and Fe $K$ absorption edges, the chiral structure of the electric quadrupole was investigated for a single crystal of ${\mathrm{DyFe}}_{3}$(${\mathrm{BO}}_{3}$)${}_{4}$, in which both Dy and Fe ions exhibit a spiral arrangement. The integrated intensity of the resonant x-ray diffraction …

[Phys. Rev. B 93, 144116] Published Mon Apr 18, 2016

]]>We discuss the influence of site occupancy on the absorption of the hydrogen isotopes H and D in thin V(001) layers. By growing V(001) under biaxial compressive strain in Fe/V(001) superlattices, the hydrogen (H as well as D) is forced to reside exclusively in octahedral (${\mathrm{O}}_{z}$) sites, even at the lowe…

[Phys. Rev. B 93, 134107] Published Fri Apr 15, 2016

]]>To explore the microscopic response of a metallic glass (MG) to an applied hydrostatic load we performed a high-pressure extended x-ray absorption fine structure (EXAFS) study of the ${\mathrm{Zr}}_{66.7}{\mathrm{Cu}}_{33.3}$ amorphous alloy. EXAFS fitting revealed that on compression, Zr-Zr pairs are strained preferentially. St…

[Phys. Rev. B 93, 144115] Published Fri Apr 15, 2016

]]>$\mathrm{N}{\mathrm{a}}_{0.5}\mathrm{B}{\mathrm{i}}_{0.5}\mathrm{Ti}{\mathrm{O}}_{3}$- based lead-free piezoelectrics exhibiting giant piezostrain are technologically interesting materials for actuator applications. The lack of clarity with regard to the structure of the nonpolar phase of this system has hindered the understanding of the structural mechanism associated…

[Phys. Rev. B 93, 134106] Published Thu Apr 14, 2016

]]>We report the thermodynamic potential for single-domain (110) thin films epitaxially grown on dissimilar cubic substrates. Using different sets of paraelectric phase elastic compliance coefficients of ${\mathrm{PbTiO}}_{3}$ single crystal, calculated from the experimental room-temperature values, we predict rotatio…

[Phys. Rev. B 93, 144113] Published Thu Apr 14, 2016

]]>We study the topological properties of three-dimensional (3D) Floquet band structures, which are defined using unitary evolution matrices rather than Hamiltonians. Previously, two-dimensional band structures of this sort have been shown to exhibit anomalous topological behaviors, such as topological…

[Phys. Rev. B 93, 144114] Published Thu Apr 14, 2016

]]>Graphite is a prototypical solid lubricant demanding a thorough understanding of its low-friction behavior. The ${E}_{2g}$(1) Raman active vibrational mode of graphite is associated with the rigid-layer relative movement of its graphene sheets. Thus, this mode can provide a good means of exploring the low …

[Phys. Rev. B 93, 144112] Published Wed Apr 13, 2016

]]>An absolute stress-density path for shocklessly compressed copper is obtained to over 450 GPa. A magnetic pressure drive is temporally tailored to generate shockless compression waves through over 2.5-mm-thick copper samples. The free-surface velocity data is analyzed for Lagrangian sound velocity u…

[Phys. Rev. B 93, 134105] Published Tue Apr 12, 2016

]]>$\mathrm{B}{\mathrm{a}}_{8}\mathrm{S}{\mathrm{i}}_{39}\mathrm{G}{\mathrm{e}}_{7}$ and $\mathrm{B}{\mathrm{a}}_{8}\mathrm{S}{\mathrm{i}}_{29}\mathrm{G}{\mathrm{e}}_{17}$ have been studied at high pressure using x-ray diffraction and x-ray absorption spectroscopy (XAS) at the Ge $K$ edge. In $\mathrm{B}{\mathrm{a}}_{8}\mathrm{S}{\mathrm{i}}_{39}\mathrm{G}{\mathrm{e}}_{7}$, a transition is observed similar to the one in $\mathrm{B}{\mathrm{a}}_{8}\mathrm{S}{\mathrm{i}}_{46}$, apparently isostructural. However, the XAS data analysis shows that the transformatio…

[Phys. Rev. B 93, 134103] Published Mon Apr 11, 2016

]]>The continuous electron bombardment of a sample during transmission electron microscopy (TEM) drives atomic-scale transformations. In earlier studies the transformations appeared to proceed as if the sample was held at an elevated temperature, and, indeed, the hypothesis of an electron-beam-induced …

[Phys. Rev. B 93, 134104] Published Mon Apr 11, 2016

]]>Simultaneous thermal, acoustic, and magnetic emission (AE and ME) measurements during thermally induced martensitic transformation in ${\text{Ni}}_{2}\text{MnGa}$ single crystals demonstrate that all three types of the above noises display many coincident peaks and the same start and finish temperatures. The amplitude a…

[Phys. Rev. B 93, 144108] Published Mon Apr 11, 2016

]]>The authors have used resonant ultrasound spectroscopy to characterize variations in the elastic and anelastic properties of GeTe associated with the ferroelectric/ferroelastic phase transition at ~625 K. These arise as a consequence of strong coupling between strain and driving order parameter, and their magnitudes are permissive of a significant order/disorder component to the transition. Remarkably, precursor softening due to dynamical disorder and Debye freezing of twin walls at low temperatures appear both to be controlled by the same thermally activated mechanism associated with small displacements of Ge within GeTe${}_{6}$ octahedra. This mechanism must also be important in constraining the stability and dynamics with respect to ferroelectric switching.

[Phys. Rev. B 93, 144109] Published Mon Apr 11, 2016

]]>An interatomic potential model that can simultaneously describe metallic, covalent, and ionic bonding is suggested by combining the second nearest-neighbor modified embedded-atom method (2NNMEAM) and the charge equilibration (Qeq) method, as a further improvement of a series of existing models. Payi…

[Phys. Rev. B 93, 144110] Published Mon Apr 11, 2016

]]>One of the key impediments to the development of ${\mathrm{BaTiO}}_{3}$-based materials as candidates to replace toxic-Pb-based solid solutions is their relatively low ferroelectric Curie temperature (${T}_{C}$). Among many potential routes that are available to modify ${T}_{C}$, ionic substitutions at the Ba and Ti sites remain…

[Phys. Rev. B 93, 144111] Published Mon Apr 11, 2016

]]>Noting the structural relationships between phases of carbon and boron carbide with phases of boron nitride and boron subnitride, we investigate their mutual solubilities using a combination of first-principles total energies supplemented with statistical mechanics to address finite temperatures. Th…

[Phys. Rev. B 93, 144107] Published Fri Apr 08, 2016

]]>Organic and inorganic lead halogen perovskites, and in particular, $\mathrm{C}{\mathrm{H}}_{3}\mathrm{N}{\mathrm{H}}_{3}\mathrm{Pb}{\mathrm{I}}_{3}$, have during the last years emerged as a class of highly efficient solar cell materials. Herein we introduce metalorganic halogen perovskite materials for energy-relevant applications based on alkaline-earth metals. Based …

[Phys. Rev. B 93, 144105] Published Thu Apr 07, 2016

]]>We perform density functional theory based first-principles calculations to identify promising alloying elements $\left(X\right)$ capable of enhancing the compressive uniaxial theoretical (ideal) strength of the fcc Ni-matrix along the $\u2329001\u232a$ direction. The alloying element belongs to a wide range of $3d,4d$, and $5d$ …

[Phys. Rev. B 93, 144106] Published Thu Apr 07, 2016

]]>${\mathrm{Ni}}_{2}\mathrm{MnGa}$ exhibits ideal ferromagnetic shape memory properties, however, brittleness and a low-temperature martensite transition hinder its technological applications motivating the search for novel materials showing better mechanical properties as well as higher transition temperatures. In this work,…

[Phys. Rev. B 93, 134102] Published Wed Apr 06, 2016

]]>The ${\mathrm{Li}}_{13}{\mathrm{Si}}_{4}$ phase is one out of several crystalline lithium silicide phases, which is a potential electrode material for lithium ion batteries and contains a high theoretical specific capacity. By means of *ab initio* methods like density functional theory (DFT) many properties such as heat capacity o…

[Phys. Rev. B 93, 144104] Published Wed Apr 06, 2016

]]>We report modifications of the ferroelectric and electrocaloric properties of ${\mathrm{BaTiO}}_{3}$ by defects. For this purpose, we have combined *ab initio* based molecular dynamics simulations with a simple model for defects. We find that different kinds of defects modify the ferroelectric transition temperatures…

[Phys. Rev. B 93, 134101] Published Tue Apr 05, 2016

]]>The electronic structure and magnetic properties of a single Fe adatom on a CuN surface have been studied using density functional theory in the local spin density approximation (LSDA), the LSDA+U approach, and the local density approximation plus dynamical mean-field theory (LDA+DMFT). The impurity…

[Phys. Rev. B 93, 140101(R)] Published Mon Apr 04, 2016

]]>Using a combination of first-principles calculation and high-resolution scanning TEM, the authors report novel structural characteristics of the ferreoelastic 90${}^{\circ}$ domain wall in PbTiO${}_{3}$. They highlight the discovery of a sharp discontinuity in the variation of the lattice parameters across the domain wall. The first-principles calculations show that oxygen vacancies prefer to cluster in the plane adjacent to the asymmetric domain walls. Understanding interaction of oxygen vacancies with domain walls is important because such defects are used to tailor properties of ferroelectric materials

[Phys. Rev. B 93, 144102] Published Mon Apr 04, 2016

]]>Semiconductors under femtosecond x-ray irradiation are transiently excited to nonequilibrium states. This can lead to observable material modifications. During the excitation and relaxation dynamics, optical properties of the solid are changing, affected by both transient electron excitation as well…

[Phys. Rev. B 93, 144101] Published Fri Apr 01, 2016

]]>We use *ab initio* calculations to estimate the formation energies of cation (transition-metal) antisite defects at oxide interfaces and to understand the basic physical effects that drive or suppress the formation of these defects. Antisite defects are found to be favored in systems with substantial …

[Phys. Rev. B 93, 104111] Published Thu Mar 31, 2016

]]>We present a scaling law for the energy and speed of transition waves in dissipative and diffusive media. By considering uniform discrete lattices and continuous solids, we show that—for arbitrary highly nonlinear many-body interactions and multistable on-site potentials—the kinetic energy per densi…

[Phys. Rev. B 93, 104109] Published Wed Mar 30, 2016

]]>We study the lowest energy configurations of an equimolar binary mixture of classical pointlike particles with charges ${Q}_{1}$ and ${Q}_{2}$, such that $q={Q}_{2}/{Q}_{1}\in [0,1]$. The particles interact pairwise via three-dimensional (3D) Coulomb potential and are confined to a 2D plane with a homogeneous neutralizing backg…

[Phys. Rev. B 93, 104110] Published Wed Mar 30, 2016

]]>Several Tl and Pb based halides and chalcohalides have recently been discovered as promising optoelectronic materials [i.e., photovoltaic (PV) and gamma-ray detection materials]. Efficient carrier transport in these materials is attributed partly to the special chemistry of $n{s}^{2}$ ions (e.g., $\mathrm{T}{\mathrm{l}}^{+},\mathrm{P}{\mathrm{b}}^{2+}$…

[Phys. Rev. B 93, 104108] Published Tue Mar 29, 2016

]]>We performed diffusion Monte Carlo (DMC) calculations of the spectroscopic properties of a large set of molecules, assessing the effect of different approximations. In systems containing elements with large atomic numbers, we show that the errors associated with the use of nonlocal mean-field-based …

[Phys. Rev. B 93, 094111] Published Mon Mar 28, 2016

]]>Mixed magnetism (the coexistence of strong and weak magnetism in one material) is regarded as the origin of the giant magnetocaloric effect (GMCE). A good example is ${(\mathrm{Mn},\mathrm{Fe})}_{2}(\mathrm{Si},\mathrm{P})$, which is established as one of the best magnetocaloric materials available. Tuning the material properties are essenti…

[Phys. Rev. B 93, 094110] Published Fri Mar 25, 2016

]]>First-principles calculations are presented to resolve the possible pressure-dependent phases of ${\mathrm{Mg}}_{2}\mathrm{Si}$. Although previous reports show that ${\mathrm{Mg}}_{2}\mathrm{Si}$ is characterized by the cubic antifluorite $Fm\overline{3}m$ structure at low pressures, the situation at higher pressures is less clear with many contradicting resul…

[Phys. Rev. B 93, 094109] Published Tue Mar 22, 2016

]]>