We present an embedded-cluster method, based on the triply irreducible local expansion formalism. It turns the Fierz ambiguity, inherent to approaches based on a bosonic decoupling of local fermionic interactions, into a convergence criterion. It is based on the approximation of the three-leg vertex...

[Phys. Rev. Lett. 119, 166401] Published Mon Oct 16, 2017

]]>A new topological semimetal state is predicted, featuring three-dimensional band crossings that manifest as perpendicular, nontrivial links.

[Phys. Rev. Lett. 119, 156401] Published Fri Oct 13, 2017

]]>We investigate the time evolution of the Kondo resonance in response to a quench by applying the time-dependent numerical renormalization group (TDNRG) approach to the Anderson impurity model in the strong correlation limit. For this purpose, we derive within the TDNRG approach a numerically tractab...

[Phys. Rev. Lett. 119, 156601] Published Fri Oct 13, 2017

]]>The interplays between different quasiparticles in solids lay the foundation for a wide spectrum of intriguing quantum effects, yet how the collective plasmon excitations affect the quantum transport of electrons remains largely unexplored. Here we provide the first demonstration that when the elect...

[Phys. Rev. Lett. 119, 156803] Published Fri Oct 13, 2017

]]>High-temperature superconductivity is closely adjacent to a long-range antiferromagnet, which is called a parent compound. In cuprates, all parent compounds are alike and carrier doping leads to superconductivity, so a unified phase diagram can be drawn. However, the properties of parent compounds f...

[Phys. Rev. Lett. 119, 157001] Published Fri Oct 13, 2017

]]>Using computer simulations, we investigate the phase behavior of a system of particles interacting with a remarkably simple repulsive square-shoulder pair potential and report the formation of a novel (and stable) pyrochlorelike crystal phase. The lattice structure of the pyrochlorelike phase formed...

[Phys. Rev. Lett. 119, 157401] Published Fri Oct 13, 2017

]]>Entanglement in quantum mechanics contradicts local realism and is a manifestation of quantum nonlocality. Its presence can be detected through the violation of Bell, or Clauser-Horne-Shimony-Holt (CHSH) inequalities. Paradigmatic quantum systems provide examples of both, nonentangled and entangled ...

[Phys. Rev. Lett. 119, 157702] Published Fri Oct 13, 2017

]]>The absorption of light to create Wannier-Mott excitons is a fundamental feature dictating the optical and photovoltaic properties of low band gap, high permittivity semiconductors. Such excitons, with an electron-hole separation an order of magnitude greater than lattice dimensions, are largely lim...

[Phys. Rev. Lett. 119, 157703] Published Fri Oct 13, 2017

]]>We study classical two-dimensional frustrated Heisenberg models with generically incommensurate ground states. A new theory for the lattice-nematic “order by disorder” transition is developed based on the self-consistent determination of the effective exchange coupling bonds. In our approach, fluctu...

[Phys. Rev. Lett. 119, 157202] Published Thu Oct 12, 2017

]]>We introduce a matrix-product state based method to efficiently obtain dynamical response functions for two-dimensional microscopic Hamiltonians. We apply this method to different phases of the Kitaev-Heisenberg model and identify characteristic dynamical features. In the ordered phases proximate to...

[Phys. Rev. Lett. 119, 157203] Published Thu Oct 12, 2017

]]>We measure x-ray magnetic circular dichroism (XMCD) spectra at the Pu ${M}_{4,5}$ absorption edges from a newly prepared high-quality single crystal of the heavy-fermion superconductor ${}^{242}\mathrm{Pu}{\mathrm{CoGa}}_{5}$, exhibiting a critical temperature ${T}_{c}=18.7\text{\hspace{0.17em}}\text{\hspace{0.17em}}\mathrm{K}$. The experiment probes the vortex phase below ${T}_{c}$ and shows that a...

[Phys. Rev. Lett. 119, 157204] Published Thu Oct 12, 2017

]]>Emergent phenomena at polar-nonpolar oxide interfaces have been studied intensely in pursuit of next-generation oxide electronics and spintronics. Here we report the disentanglement of critical thicknesses for electron reconstruction and the emergence of ferromagnetism in polar-mismatched ${\mathrm{LaMnO}}_{3}/{\mathrm{SrT...}}_{}$

[Phys. Rev. Lett. 119, 156801] Published Wed Oct 11, 2017

]]>We study hole spin resonance in a $p$-channel silicon metal-oxide-semiconductor field-effect transistor. In the subthreshold region, the measured source-drain current reveals a double dot in the channel. The observed spin resonance spectra agree with a model of strongly coupled two-spin states in the ...

[Phys. Rev. Lett. 119, 156802] Published Wed Oct 11, 2017

]]>We suggest that a randomization of the pseudodipolar interaction in the spin-orbit-generated low-energy Hamiltonian of ${\mathrm{YbMgGaO}}_{4}$ due to an inhomogeneous charge environment from a natural mixing of ${\mathrm{Mg}}^{2+}$ and ${\mathrm{Ga}}^{3+}$ can give rise to orientational spin disorder and mimic a spin-liquid-like state. In the ab...

[Phys. Rev. Lett. 119, 157201] Published Wed Oct 11, 2017

]]>Hybrid improper ferroelectricity (HIF) denotes a new class of polar instability by the mixture of two octahedral-distortion modes and can feature the coexistence of abundant head-to-head and tail-to-tail polar domains, of which the domain walls tend to be charged due to the respective screening char...

[Phys. Rev. Lett. 119, 157601] Published Tue Oct 10, 2017

]]>Induced transfer of charge carriers is demonstrated in a graphene-based field-effect transistor, leading to a quantum Hall plateau.

[Phys. Rev. Lett. 119, 157701] Published Tue Oct 10, 2017

]]>The ac magnetoconductance of bulk InSb at THz frequencies in high magnetic fields, as measured by the transmission of THz radiation, shows a field-induced transmission, which at high temperatures ($\approx 100\text{\hspace{0.17em}}\text{\hspace{0.17em}}\mathrm{K}$) is well explained with classical magnetoplasma effects (helicon waves). However, at low temper...

[Phys. Rev. Lett. 119, 146603] Published Fri Oct 06, 2017

]]>We construct a low energy effective theory of anisotropic fractional quantum Hall (FQH) states. We develop a formalism similar to that used in the bimetric approach to massive gravity, and apply it to describe Abelian anisotropic FQH states in the presence of external electromagnetic and geometric b...

[Phys. Rev. Lett. 119, 146602] Published Thu Oct 05, 2017

]]>Electric fields applied on either side of a thin, semiconducting transition-metal dichalcogenide create a superconducting layer atop a metallic layer within the material.

[Phys. Rev. Lett. 119, 147002] Published Thu Oct 05, 2017

]]>We study the frequency-dependent conductivity of nodal line semimetals (NLSMs), focusing on the effects of carrier density and energy dispersion on the nodal line. We find that the low-frequency conductivity has a rich spectral structure which can be understood using scaling rules derived from the g...

[Phys. Rev. Lett. 119, 147402] Published Thu Oct 05, 2017

]]>We introduce a method for breaking Lorentz reciprocity based upon the noncommutation of frequency conversion and delay. The method requires no magnetic materials or resonant physics, allowing for the design of scalable and broadband nonreciprocal circuits. With this approach, two types of gyrators—u...

[Phys. Rev. Lett. 119, 147703] Published Thu Oct 05, 2017

]]>We show that carbon nanotubes (CNT) can be driven through a topological phase transition using either strain or a magnetic field. This can naturally lead to Jackiw-Rebbi soliton states carrying fractionalized charges, similar to those found in a domain wall in the Su-Schrieffer-Heeger model, in a se...

[Phys. Rev. Lett. 119, 147704] Published Thu Oct 05, 2017

]]>Proximity orbital and spin-orbit effects of bilayer graphene on monolayer ${\mathrm{WSe}}_{2}$ are investigated from first principles. We find that the built-in electric field induces an orbital band gap of about 10 meV in bilayer graphene. Remarkably, the proximity spin-orbit splitting for holes is 2 orders of mag...

[Phys. Rev. Lett. 119, 146401] Published Wed Oct 04, 2017

]]>Non-Fermi liquids are metals that cannot be adiabatically deformed into free fermion states. We argue for the existence of “non-Fermi glasses,” phases of interacting disordered fermions that are fully many-body localized (MBL), yet cannot be deformed into an Anderson insulator without an eigenstate ...

[Phys. Rev. Lett. 119, 146601] Published Wed Oct 04, 2017

]]>An external off-resonant pumping is proposed as a tool to control the Dzyaloshinskii-Moriya interaction (DMI) in ferromagnetic layers with strong spin-orbit coupling. Combining theoretical analysis with numerical simulations for an $s\text{\u2212}d$-like model, we demonstrate that linearly polarized off-resonant ...

[Phys. Rev. Lett. 119, 147202] Published Wed Oct 04, 2017

]]>The recent synthesis of two-dimensional staggered materials opens up burgeoning opportunities to study optical spin-orbit interactions in semiconducting Dirac-like systems. We unveil topological phase transitions in the photonic spin Hall effect in the graphene family materials. It is shown that an ...

[Phys. Rev. Lett. 119, 147401] Published Wed Oct 04, 2017

]]>We have investigated the phase dynamics of a superconducting tunnel junction at ultralow temperatures in the presence of high damping, where the interaction with environmental degrees of freedom represents the leading energy scale. In this regime, theory predicts the dynamics to follow a generalizat...

[Phys. Rev. Lett. 119, 147702] Published Wed Oct 04, 2017

]]>Time-reversal invariant superconductors in three dimensions may contain nodal lines in the Brillouin zone, which behave as Wilson loops of 3D momentum-space Chern-Simons theory of the Berry connection. Here we study the conditions of realizing linked nodal lines (Wilson loops), which yield a topolog...

[Phys. Rev. Lett. 119, 147001] Published Mon Oct 02, 2017

]]>A rare example of a highly frustrated metal is identified, where the frustration is due to competing exchange interactions of spins, and not due to the spin geometry.

[Phys. Rev. Lett. 119, 147201] Published Mon Oct 02, 2017

]]>Coupling between a crystal of di(phenyl)-(2,4,6-trinitrophenyl)iminoazanium radicals and a superconducting microwave resonator is investigated in a circuit quantum electrodynamics (circuit QED) architecture. The crystal exhibits paramagnetic behavior above 4 K, with antiferromagnetic correlations ap...

[Phys. Rev. Lett. 119, 147701] Published Mon Oct 02, 2017

]]>The ground state of the quantum kagome antiferromagnet Zn-brochantite, ${\mathrm{ZnCu}}_{3}(\mathrm{OH}{)}_{6}{\mathrm{SO}}_{4}$, which is one of only a few known spin-liquid (SL) realizations in two or three dimensions, has been described as a gapless SL with a spinon Fermi surface. Employing nuclear magnetic resonance in a broad magnetic-fi...

[Phys. Rev. Lett. 119, 137205] Published Fri Sep 29, 2017

]]>We predict the existence of triple point fermions in the band structure of several half-Heusler topological insulators by *ab initio* calculations and the Kane model. We find that many half-Heusler compounds exhibit multiple triple points along four independent ${C}_{3}$ axes, through which the doubly degene...

[Phys. Rev. Lett. 119, 136401] Published Thu Sep 28, 2017

]]>We uncover two anomalous features in the nonlocal transport behavior of two-dimensional metallic materials with spin-orbit coupling. First, the nonlocal resistance can have negative values and oscillate with distance, even in the absence of a magnetic field. Second, the oscillations of the nonlocal ...

[Phys. Rev. Lett. 119, 136804] Published Thu Sep 28, 2017

]]>Plasmons, the collective excitations of electrons in the bulk or at the surface, play an important role in the properties of materials, and have generated the field of “plasmonics.” We report the observation of a highly unusual acoustic plasmon mode on the surface of a three-dimensional topological ...

[Phys. Rev. Lett. 119, 136805] Published Thu Sep 28, 2017

]]>The quantum Hall effect is usually observed in 2D systems. We show that the Fermi arcs can give rise to a distinctive 3D quantum Hall effect in topological semimetals. Because of the topological constraint, the Fermi arc at a single surface has an open Fermi surface, which cannot host the quantum Ha...

[Phys. Rev. Lett. 119, 136806] Published Thu Sep 28, 2017

]]>Recently, it has been predicted that the Andreev bound state spectrum of four-terminal Josephson junctions may possess zero-energy Weyl singularities. Using one superconducting phase as a control parameter, these singularities are associated with topological transitions between time-reversal symmetr...

[Phys. Rev. Lett. 119, 136807] Published Thu Sep 28, 2017

]]>The current-nonlinear Hall effect or second harmonic Hall voltage is widely used as one of the methods for estimating charge-spin conversion efficiency, which is attributed to the magnetization oscillation by spin-orbit torque (SOT). Here, we argue the second harmonic Hall voltage under a large in-p...

[Phys. Rev. Lett. 119, 137204] Published Thu Sep 28, 2017

]]>Based on a first-principles based multiscale approach, we study the polarity $P$ of ferroelastic twin walls in ${\mathrm{SrTiO}}_{3}$. In addition to flexoelectricity, which was pointed out before, we identify two new mechanisms that crucially contribute to $P$: a direct “rotopolar” coupling to the gradients of the ant...

[Phys. Rev. Lett. 119, 137601] Published Thu Sep 28, 2017

]]>We compute the transient dynamics of phonons in contact with high energy “hot” charge carriers in 12 polar and nonpolar semiconductors, using a first-principles Boltzmann transport framework. For most materials, we find that the decay in electronic temperature departs significantly from a single-exp...

[Phys. Rev. Lett. 119, 136602] Published Wed Sep 27, 2017

]]>Using polarization-resolved resonant Raman spectroscopy, we explore collective spin excitations of the chiral surface states in a three dimensional topological insulator, ${\mathrm{Bi}}_{2}{\mathrm{Se}}_{3}$. We observe a sharp peak at 150 meV in the pseudovector ${A}_{2}$ symmetry channel of the Raman spectra. By comparing the data wi...

[Phys. Rev. Lett. 119, 136802] Published Wed Sep 27, 2017

]]>Under certain conditions, conductance peaks at zero electrical bias may be considered as signatures of Majorana bound states.

[Phys. Rev. Lett. 119, 136803] Published Wed Sep 27, 2017

]]>Skyrmions are nanometric spin whirls that can be stabilized in magnets lacking inversion symmetry. The properties of isolated Skyrmions embedded in a ferromagnetic background have been intensively studied. We show that single Skyrmions and clusters of Skyrmions can also form in the helical phase and...

[Phys. Rev. Lett. 119, 137201] Published Wed Sep 27, 2017

]]>We demonstrate a new method for the detection of the spin-chemical potential in topological insulators using spin-polarized four-probe scanning tunneling microscopy on *in situ* cleaved ${\mathrm{Bi}}_{2}{\mathrm{Te}}_{2}\mathrm{Se}$ surfaces. Two-dimensional (2D) surface and 3D bulk conductions are separated quantitatively via variable pr...

[Phys. Rev. Lett. 119, 137202] Published Wed Sep 27, 2017

]]>The existence of novel magnetic circular dichroism in core-level x-ray emission is reported. By means of circular polarization analysis, the dichroic effect of the Fe ${K\alpha}_{1}$ emission spectrum is measured on an Fe single crystal. The observed dichroic effect (12%) is remarkably large, if one takes into ...

[Phys. Rev. Lett. 119, 137203] Published Wed Sep 27, 2017

]]>Using time-resolved Kerr rotation, we measure the spin-valley dynamics of resident electrons and holes in single charge-tunable monolayers of the archetypal transition-metal dichalcogenide (TMD) semiconductor ${\mathrm{WSe}}_{2}$. In the $n$-type regime, we observe long ($\sim 130\text{\hspace{0.17em}}\text{\hspace{0.17em}}\mathrm{ns}$) polarization relaxation of electrons...

[Phys. Rev. Lett. 119, 137401] Published Wed Sep 27, 2017

]]>The enhancement of optical forces has enabled a variety of technological applications that rely on the optical control of small objects and devices. Unfortunately, optical forces are still too small for the convenient actuation of integrated switches and waveguide couplers. Here we show how the opti...

[Phys. Rev. Lett. 119, 137402] Published Wed Sep 27, 2017

]]>Graphite is a model system for the study of three-dimensional electrons and holes in the magnetic quantum limit, in which the charges are confined to the lowest Landau levels. We report magneto-transport measurements in pulsed magnetic fields up to 60 T, which resolve the collapse of two charge dens...

[Phys. Rev. Lett. 119, 136601] Published Tue Sep 26, 2017

]]>Some time-reversal symmetric topological orders are anomalous in that they cannot be realized in strictly two-dimensional systems; instead, they can only be realized on the surface of three-dimensional symmetry-protected topological phases. We propose two quantities, which we call *anomaly indicators*...

[Phys. Rev. Lett. 119, 136801] Published Tue Sep 26, 2017

]]>We show that a properly dc-biased Josephson junction in series with two microwave resonators of different frequencies emits photon pairs in the resonators. By measuring auto- and intercorrelations of the power leaking out of the resonators, we demonstrate two-mode amplitude squeezing below the class...

[Phys. Rev. Lett. 119, 137001] Published Tue Sep 26, 2017

]]>We calculate the plasmon dispersion relation for Coulomb coupled metallic armchair graphene nanoribbons and doped monolayer graphene. The crossing of the plasmon curves, which occurs for uncoupled 1D and 2D systems, is split by the interlayer Coulomb coupling into a lower and an upper plasmon branch...

[Phys. Rev. Lett. 119, 126801] Published Fri Sep 22, 2017

]]>The Lieb-Schultz-Mattis (LSM) theorem and its extensions forbid trivial phases from arising in certain quantum magnets. Constraining infrared behavior with the ultraviolet data encoded in the microscopic lattice of spins, these theorems tie the absence of spontaneous symmetry breaking to the emergen...

[Phys. Rev. Lett. 119, 127202] Published Fri Sep 22, 2017

]]>A full description of a magnetic sample includes a correct treatment of the boundary conditions (BCs). This is in particular important in thin film systems, where even bulk properties might be modified by the properties of the boundary of the sample. We study generic ferromagnets with broken spatial...

[Phys. Rev. Lett. 119, 127203] Published Fri Sep 22, 2017

]]>In conventional insulating magnets, heat is carried by magnons and phonons. In contrast, when the magnets harbor a quantum spin liquid state, emergent quasiparticles from the fractionalization of quantum spins can carry heat. Here, we investigate unconventional thermal transport yielded by such exot...

[Phys. Rev. Lett. 119, 127204] Published Fri Sep 22, 2017

]]>In stimulated Raman scattering, two incident optical waves induce a force oscillating at the difference of the two light frequencies. This process has enabled important applications such as the excitation and coherent control of phonons and magnons by femtosecond laser pulses. Here, we experimentall...

[Phys. Rev. Lett. 119, 127402] Published Fri Sep 22, 2017

]]>The two-dimensional character and reduced screening in monolayer transition-metal dichalcogenides (TMDs) lead to the ubiquitous formation of robust excitons with binding energies orders of magnitude larger than in bulk semiconductors. Focusing on neutral excitons, bound electron-hole pairs that domi...

[Phys. Rev. Lett. 119, 127403] Published Fri Sep 22, 2017

]]>The electric field manipulation of the Rashba spin-orbit coupling effects provides a route to electrically control spins, constituting the foundation of the field of semiconductor spintronics. In general, the strength of the Rashba effects depends linearly on the applied electric field and is signif...

[Phys. Rev. Lett. 119, 126401] Published Thu Sep 21, 2017

]]>A ferromagnetic quantum critical point is thought not to exist in two- and three-dimensional metallic systems yet is realized in the Kondo lattice compound ${\mathrm{YbNi}}_{4}(\mathrm{P},\mathrm{As}{)}_{2}$, possibly due to its one-dimensionality. It is crucial to investigate the dimensionality of the Fermi surface of ${\mathrm{YbNi}}_{4}{\mathrm{P}}_{2}$ experiment...

[Phys. Rev. Lett. 119, 126402] Published Thu Sep 21, 2017

]]>We present a magnetic phase diagram of rare-earth pyrochlore ${\mathrm{Yb}}_{2}{\mathrm{Ti}}_{2}{\mathrm{O}}_{7}$ in a $\u27e8111\u27e9$ magnetic field. Using heat capacity, magnetization, and neutron scattering data, we show an unusual field dependence of a first-order phase boundary, wherein a small applied field increases the ordering temperature. The...

[Phys. Rev. Lett. 119, 127201] Published Thu Sep 21, 2017

]]>Semiconductor microcavities in the strong-coupling regime exhibit an energy scale in the terahertz (THz) frequency range, which is fixed by the Rabi splitting between the upper and lower exciton-polariton states. While this range can be tuned by several orders of magnitude using different excitonic ...

[Phys. Rev. Lett. 119, 127401] Published Mon Sep 18, 2017

]]>SnSe has emerged as an efficient thermoelectric material since a high value of the thermoelectric figure of merit ($ZT$) has been reported recently. Here we show with systematic angle resolved photoemission spectroscopy data that the low-lying electronic structures of undoped and hole-doped SnSe cryst...

[Phys. Rev. Lett. 119, 116401] Published Wed Sep 13, 2017

]]>The transport properties of nanostructured systems are deeply affected by the geometry of the effective connections to metallic leads. In this work we derive a conductance expression for a class of interacting systems whose connectivity geometries do not meet the Meir-Wingreen proportional coupling ...

[Phys. Rev. Lett. 119, 116801] Published Tue Sep 12, 2017

]]>Motivated by recent experiments with proximitized nanowires, we study a mesoscopic $s$-wave superconductor connected via point contacts to normal-state leads. We demonstrate that at energies below the charging energy the system is described by the two-channel Kondo model, which can be brought to the q...

[Phys. Rev. Lett. 119, 116802] Published Tue Sep 12, 2017

]]>In-plane hole $g$ factors measured in quantum point contacts based on $p$-type heterostructures strongly depend on the orientation of the magnetic field with respect to the electric current. This effect, first reported a decade ago and confirmed in a number of publications, has remained an open problem....

[Phys. Rev. Lett. 119, 116803] Published Tue Sep 12, 2017

]]>Using first-principles-based simulations merging an effective Hamiltonian scheme with scaling, symmetry, and topological arguments, we find that an overlooked Berezinskii-Kosterlitz-Thouless ($\mathsf{B}\mathsf{K}\mathsf{T}$) phase sustained by quasicontinuous symmetry emerges between the ferroelectric phase and the paraelectri...

[Phys. Rev. Lett. 119, 117601] Published Tue Sep 12, 2017

]]>We calculate the effect of impurities on the superconducting phase diagram of transition metal dichalcogenide monolayers in the presence of an in-plane magnetic field. Because of strong intrinsic spin-orbit coupling, the upper critical field greatly surpasses the Pauli limit at low temperatures. We ...

[Phys. Rev. Lett. 119, 117001] Published Mon Sep 11, 2017

]]>We study longitudinal magnetotransport in a disordered Weyl semimetal taking into account localization effects in the vicinity of a Weyl node exactly. In a magnetic field, a single chiral Landau level coexists with a number of conventional nonchiral levels. Disorder scattering mixes these topologica...

[Phys. Rev. Lett. 119, 106601] Published Fri Sep 08, 2017

]]>Analysis of the magnetoresistance of topological insulators indicates that the bulk of these materials is more topologically interesting than previously thought.

[Phys. Rev. Lett. 119, 106602] Published Fri Sep 08, 2017

]]>We present a new electromagnetic mode that forms at the interface between two planar surfaces laid side by side in free space, effectively guiding energy along an infinitesimal, one-dimensional line. It is shown that this mode occurs when the boundaries have complementary surface impedances, and it ...

[Phys. Rev. Lett. 119, 106802] Published Fri Sep 08, 2017

]]>A first-principles search among possible rare earth hydrogen clathrate structures under high pressure predicts that one of them, YH${}_{10}$, is a potential room-temperature superconductor with a $T$${}_{c}$ of up to 303 K, at 400 GPa pressure.

[Phys. Rev. Lett. 119, 107001] Published Fri Sep 08, 2017

]]>Short-range charge-density wave correlations are ubiquitous in underdoped cuprates. They are largely confined to the copper-oxygen planes and typically oscillate out of phase from one unit cell to the next in the $c$ direction. Recently, it was found that a considerably longer-range charge-density wav...

[Phys. Rev. Lett. 119, 107002] Published Fri Sep 08, 2017

]]>Interfacial phonons between iron-based superconductors (FeSCs) and perovskite substrates have received considerable attention due to the possibility of enhancing preexisting superconductivity. Using scanning tunneling spectroscopy, we studied the correlation between superconductivity and $e\text{\u2212}\text{ph}$ intera...

[Phys. Rev. Lett. 119, 107003] Published Fri Sep 08, 2017

]]>A joint theoretical and experimental investigation is performed to understand the underlying physics of laser-induced demagnetization in Ni and Co films with varying thicknesses excited by 10 fs optical pulses. Experimentally, the dynamics of spins is studied by determining the time-dependent amplit...

[Phys. Rev. Lett. 119, 107203] Published Fri Sep 08, 2017

]]>We generalize the concept of the spin-momentum locking to magnonic systems and derive the formula to calculate the spin expectation value for one-magnon states of general two-body spin Hamiltonians. We give no-go conditions for magnon spin to be independent of momentum. As examples of the magnon spi...

[Phys. Rev. Lett. 119, 107205] Published Fri Sep 08, 2017

]]>Discovered in high-energy physics, the chiral anomaly has recently made way to materials science by virtue of Weyl semimetals (WSM). Thus far, the main efforts to probe the chiral anomaly in WSM have concentrated on electronic phenomena. Here, we show that the chiral anomaly can have a large impact ...

[Phys. Rev. Lett. 119, 107401] Published Fri Sep 08, 2017

]]>Half-metallicity (full spin polarization of the Fermi surface) usually occurs in strongly correlated electron systems. We demonstrate that doping a spin-density wave insulator in the weak-coupling regime may also stabilize half-metallic states. In the absence of doping, the spin-density wave is form...

[Phys. Rev. Lett. 119, 107601] Published Fri Sep 08, 2017

]]>We investigate extrinsic wormholelike twist defects that effectively increase the genus of space in lattice versions of multicomponent fractional quantum Hall systems. Although the original band structure is distorted by these defects, leading to localized midgap states, we find that a new lowest fl...

[Phys. Rev. Lett. 119, 106801] Published Thu Sep 07, 2017

]]>Ultrafast x-ray scattering studies of the topological Skyrmion phase in ${\mathrm{Cu}}_{2}{\mathrm{OSeO}}_{3}$ show the dynamics to be strongly dependent on the excitation energy and fluence. At high photon energies, where the electron-spin scattering cross section is relatively high, the excitation of the topological Skyrmion p...

[Phys. Rev. Lett. 119, 107204] Published Thu Sep 07, 2017

]]>A comprehensive understanding of spin-polarized photoemission is crucial for accessing the electronic structure of spin-orbit coupled materials. Yet, the impact of the final state in the photoemission process on the photoelectron spin has been difficult to assess in these systems. We present experim...

[Phys. Rev. Lett. 119, 106401] Published Tue Sep 05, 2017

]]>Twisted graphene bilayers develop highly localized states around $AA$-stacked regions for small twist angles. We show that interaction effects may induce either an antiferromagnetic or a ferromagnetic (FM) polarization of said regions, depending on the electrical bias between layers. Remarkably, FM-po...

[Phys. Rev. Lett. 119, 107201] Published Tue Sep 05, 2017

]]>Proposed as a fundamental symmetry describing our Universe, spacetime supersymmetry (SUSY) has not been discovered yet in nature. Nonetheless, it has been predicted that SUSY may emerge in low-energy physics of quantum materials such as topological superconductors and Weyl semimetals. Here, by perfo...

[Phys. Rev. Lett. 119, 107202] Published Tue Sep 05, 2017

]]>The nonlinear response of soft-mode excitations in polycrystalline acetylsalicylic acid (aspirin) is studied with two-dimensional terahertz spectroscopy. We demonstrate that the correlation of ${\mathrm{CH}}_{3}$ rotational modes with collective oscillations of $\pi $ electrons drives the system into the nonperturbative...

[Phys. Rev. Lett. 119, 097404] Published Fri Sep 01, 2017

]]>We report infrared studies of $A{\mathrm{Fe}}_{2}{\mathrm{As}}_{2}$ ($A=\mathrm{Ba}$, Sr), two representative parent compounds of iron-arsenide superconductors, at magnetic fields ($B$) up to 17.5 T. Optical transitions between Landau levels (LLs) were observed in the antiferromagnetic states of these two parent compounds. Our observation of...

[Phys. Rev. Lett. 119, 096401] Published Thu Aug 31, 2017

]]>We demonstrate optical spin polarization of the neutrally charged silicon-vacancy defect in diamond (${\mathrm{SiV}}^{0}$), an $S=1$ defect which emits with a zero-phonon line at 946 nm. The spin polarization is found to be most efficient under resonant excitation, but nonzero at below-resonant energies. We measure a...

[Phys. Rev. Lett. 119, 096402] Published Thu Aug 31, 2017

]]>We consider the response of the density of a fermion ensemble to an applied weak static magnetic field. It is known that, for a noninteracting Fermi gas, this response is fully characterized by the Fermi volume and the Berry curvature on the Fermi surface. Here we show the same result holds for inte...

[Phys. Rev. Lett. 119, 096601] Published Thu Aug 31, 2017

]]>Spin excitations in the overdoped high temperature superconductors ${\mathrm{Tl}}_{2}{\mathrm{Ba}}_{2}{\mathrm{CuO}}_{6+\delta}$ and $(\mathrm{Bi},\mathrm{Pb}{)}_{2}(\mathrm{Sr},\mathrm{La}{)}_{2}{\mathrm{CuO}}_{6+\delta}$ were investigated by resonant inelastic x-ray scattering (RIXS) as functions of doping and detuning of the incoming photon energy above the $\mathrm{Cu}\text{\u2212}{L}_{3}$ absorption peak. The RIXS spectra at optimal do...

[Phys. Rev. Lett. 119, 097001] Published Thu Aug 31, 2017

]]>In systems having an anisotropic electronic structure, such as the layered materials graphite, graphene, and cuprates, impulsive light excitation can coherently stimulate specific bosonic modes, with exotic consequences for the emergent electronic properties. Here we show that the population of ${E}_{2g}$ ...

[Phys. Rev. Lett. 119, 097002] Published Thu Aug 31, 2017

]]>The emergence of $1/f$ noise from an aggregate of $1/{f}^{2}$ noise signals in magnetic nanodots undergoing random telegraph oscillations in their magnetization is reported. This emergence is found to occur with as few as two random telegraph noise (RTN) oscillators producing $1/f$ noise across two decades of ...

[Phys. Rev. Lett. 119, 097201] Published Thu Aug 31, 2017

]]>We propose that resonant inelastic x-ray scattering (RIXS) is an effective probe of the fractionalized excitations in three-dimensional (3D) Kitaev spin liquids. While the non-spin-conserving RIXS responses are dominated by the gauge-flux excitations and reproduce the inelastic-neutron-scattering re...

[Phys. Rev. Lett. 119, 097202] Published Thu Aug 31, 2017

]]>The directed-loop quantum Monte Carlo method is generalized to the case of retarded interactions. Using the path integral, fermion-boson or spin-boson models are mapped to actions with retarded interactions by analytically integrating out the bosons. This yields an exact algorithm that combines the ...

[Phys. Rev. Lett. 119, 097401] Published Thu Aug 31, 2017

]]>Aggregates of interacting molecules can exhibit electronically excited states that are coherently delocalized over many molecules. This can lead to a strong enhancement of the fluorescence decay rate which is referred to as superradiance (SR). To date, the temperature dependence of SR is described b...

[Phys. Rev. Lett. 119, 097402] Published Thu Aug 31, 2017

]]>We study exciton-polariton nonlinear optical fluids in the high momentum waveguide regime for the first time. We demonstrate the formation of dark solitons with the expected dependence of width on fluid density for both main classes of soliton-forming fluid defects. The results are well described by...

[Phys. Rev. Lett. 119, 097403] Published Thu Aug 31, 2017

]]>We present a study of Andreev quantum dots fabricated with small-diameter (30 nm) Si-doped InAs nanowires where the Fermi level can be tuned across a mobility edge separating localized states from delocalized states. The transition to the insulating phase is identified by a drop in the amplitude and...

[Phys. Rev. Lett. 119, 097701] Published Thu Aug 31, 2017

]]>We demonstrate a single atom maser consisting of a semiconductor double quantum dot (DQD) that is embedded in a high-quality-factor microwave cavity. A finite bias drives the DQD out of equilibrium, resulting in sequential single electron tunneling and masing. We develop a dynamic tuning protocol th...

[Phys. Rev. Lett. 119, 097702] Published Thu Aug 31, 2017

]]>Spin accumulation due to the spin Hall effect has, for the first time, been detected directly, rather than inferred indirectly, in nonmagnetic conductors.

[Phys. Rev. Lett. 119, 087203] Published Fri Aug 25, 2017

]]>We show that the anisotropy of the effective spin model for the dimer Mott insulator phase of $\kappa $-$(\mathrm{BEDT}\text{\u2212}\mathrm{TTF}{)}_{2}X$ salts is dramatically different from that of the underlying tight-binding model. Intradimer quantum interference results in a model of coupled spin chains, where frustrated interchain interac...

[Phys. Rev. Lett. 119, 087204] Published Fri Aug 25, 2017

]]>Optoelectronic excitations in monolayer ${\mathrm{MoS}}_{2}$ manifest from a hierarchy of electrically tunable, Coulombic free-carrier and excitonic many-body phenomena. Investigating the fundamental interactions underpinning these phenomena—critical to both many-body physics exploration and device applications—pre...

[Phys. Rev. Lett. 119, 087401] Published Fri Aug 25, 2017

]]>We employ a recently developed computational many-body technique to study for the first time the half-filled Anderson-Hubbard model at finite temperature and arbitrary correlation $U$ and disorder $V$ strengths. Interestingly, the narrow zero temperature metallic range induced by disorder from the Mott ...

[Phys. Rev. Lett. 119, 086601] Published Thu Aug 24, 2017

]]>We elucidate the origin of the phonon-mediated superconductivity in $2H$-${\mathrm{NbS}}_{2}$ using the *ab initio* anisotropic Migdal-Eliashberg theory including Coulomb interactions. We demonstrate that superconductivity is associated with Fermi surface hot spots exhibiting an unusually strong electron-phonon interac...

[Phys. Rev. Lett. 119, 087003] Published Thu Aug 24, 2017

]]>We theoretically study the interplay between bulk Weyl electrons and magnetic topological defects, including magnetic domains, domain walls, and ${\mathbb{Z}}_{6}$ vortex lines, in the antiferromagnetic Weyl semimetals ${\mathrm{Mn}}_{3}\mathrm{Sn}$ and ${\mathrm{Mn}}_{3}\mathrm{Ge}$ with negative vector chirality. We argue that these materials possess a hierarchy...

[Phys. Rev. Lett. 119, 087202] Published Thu Aug 24, 2017

]]>We report on the nonequilibrium dynamics of the electronic structure of the layered semiconductor ${\mathrm{Ta}}_{2}{\mathrm{NiSe}}_{5}$ investigated by time- and angle-resolved photoelectron spectroscopy. We show that below the critical excitation density of ${F}_{C}=0.2\text{\hspace{0.17em}}\text{\hspace{0.17em}}\mathrm{mJ}\text{\hspace{0.17em}}{\mathrm{cm}}^{-2}$, the band gap *narrows* transiently, while it is *enhance...*

[Phys. Rev. Lett. 119, 086401] Published Wed Aug 23, 2017

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