We present the theory of quasiparticle transport in perturbatively small inhomogeneous magnetic fields across the ballistic-to-hydrodynamic crossover. In the hydrodynamic limit, the resistivity $\rho $ generically grows proportionally to the rate of momentum-conserving electron-electron collisions at larg...

[Phys. Rev. Lett. 120, 116603] Published Fri Mar 16, 2018

]]>In underdoped cuprates, an incommensurate charge density wave (CDW) order is known to coexist with superconductivity. A dip in ${T}_{c}$ at the hole doping level where the CDW is strongest (${n}_{p}\simeq 0.12$) suggests that CDW order may suppress superconductivity. We investigate the interplay of charge order with su...

[Phys. Rev. Lett. 120, 117002] Published Fri Mar 16, 2018

]]>An ultimate goal of spintronics is to control magnetism via electrical means. One promising way is to utilize a current-induced spin-orbit torque (SOT) originating from the strong spin-orbit coupling in heavy metals and their interfaces to switch a single perpendicularly magnetized ferromagnetic lay...

[Phys. Rev. Lett. 120, 117703] Published Fri Mar 16, 2018

]]>We consider a two-dimensional electron gas (2DEG) in the quantum Hall regime in the presence of a Zeeman field, with the Fermi level tuned to a filling factor of $\nu =1$. We show that, in the presence of spin-orbit coupling, contacting the 2DEG with a narrow strip of an $s$-wave superconductor produces a ...

[Phys. Rev. Lett. 120, 116801] Published Thu Mar 15, 2018

]]>Recently, the topological physics in artificial crystals for classical waves has become an emerging research area. In this Letter, we propose a unique bilayer design of sonic crystals that are constructed by two layers of coupled hexagonal array of triangular scatterers. Assisted by the additional l...

[Phys. Rev. Lett. 120, 116802] Published Thu Mar 15, 2018

]]>We show using numerical simulations that slowly driven Skyrmions interacting with random pinning move via correlated jumps or avalanches. The avalanches exhibit power-law distributions in their duration and size, and the average avalanche shape for different avalanche durations can be scaled to a un...

[Phys. Rev. Lett. 120, 117203] Published Thu Mar 15, 2018

]]>The honeycomb Kitaev-Heisenberg model is a source of a quantum spin liquid with Majorana fermions and gauge flux excitations as fractional quasiparticles. Here we unveil the highly unusual low-temperature heat conductivity $\kappa $ of $\alpha \text{\u2212}{\mathrm{RuCl}}_{3}$, a prime candidate for realizing such physics: beyond a magnetic...

[Phys. Rev. Lett. 120, 117204] Published Thu Mar 15, 2018

]]>Point defects in wide-band-gap semiconductors are emerging as versatile resources for nanoscale sensing and quantum information science, but our understanding of the photoionization dynamics is presently incomplete. Here, we use two-color confocal microscopy to investigate the dynamics of charge in ...

[Phys. Rev. Lett. 120, 117401] Published Thu Mar 15, 2018

]]>A proposed dipole source of electromagnetic waves can selectively couple its emission into either of two neighboring waveguides.

[Phys. Rev. Lett. 120, 117402] Published Thu Mar 15, 2018

]]>Theoretical predictions suggest a quantum battery could be implemented in either nanofabricated semiconductor quantum dots in a photonic cavity or superconducting qubits.

[Phys. Rev. Lett. 120, 117702] Published Thu Mar 15, 2018

]]>Trap-assisted recombination is identified as the mechanism responsible for the negative contribution to the capacitance in bipolar organic diodes.

[Phys. Rev. Lett. 120, 116602] Published Wed Mar 14, 2018

]]>Terahertz-pulse excitation experiments provide evidence for a Higgs mode in a d-wave-type, high-temperature cuprate superconductor.

[Phys. Rev. Lett. 120, 117001] Published Wed Mar 14, 2018

]]>Experiments on the optical writing and erasing of magnetic skyrmions in FeGe indicate that more efficient skyrmion generation can be achieved in a cooled sample.

[Phys. Rev. Lett. 120, 117201] Published Wed Mar 14, 2018

]]>A previously unseen macroscopic degeneracy is predicted in spin-1/2 kagome antiferromagnets, explaining the presence and absence of spin liquids in various regions of the phase diagram.

[Phys. Rev. Lett. 120, 117202] Published Tue Mar 13, 2018

]]>Fundamental research and technological applications of topological insulators are hindered by the rarity of materials exhibiting a robust topologically nontrivial phase, especially in two dimensions. Here, by means of extensive first-principles calculations, we propose a novel quantum spin Hall insu...

[Phys. Rev. Lett. 120, 117701] Published Tue Mar 13, 2018

]]>Using exact quantum Monte Carlo calculations, we examine the interplay between localization of electronic states driven by many-body correlations and that by randomness in a two-dimensional system featuring linearly vanishing density of states at the Fermi level. A novel disorder-induced nonmagnetic...

[Phys. Rev. Lett. 120, 116601] Published Mon Mar 12, 2018

]]>The unique properties of topological semimetals have strongly driven efforts to seek for new topological phases and related materials. Here, we identify a critical condition for the existence of intersecting nodal rings (INRs) in symmorphic crystals, and further classify all possible kinds of INRs w...

[Phys. Rev. Lett. 120, 106403] Published Fri Mar 09, 2018

]]>We study Thouless pumping out of the adiabatic limit. Our findings show that despite its topological nature, this phenomenon is not generically robust to nonadiabatic effects. Indeed, we find that the Floquet diagonal ensemble value of the pumped charge shows a deviation from the topologically quant...

[Phys. Rev. Lett. 120, 106601] Published Fri Mar 09, 2018

]]>We demonstrate strong anisotropic spin-orbit interaction (SOI) in graphene induced by monolayer ${\mathrm{WS}}_{2}$. Direct comparison between graphene-monolayer ${\mathrm{WS}}_{2}$ and graphene-bulk ${\mathrm{WS}}_{2}$ systems in magnetotransport measurements reveals that monolayer transition metal dichalcogenide can induce much stronger SOI tha...

[Phys. Rev. Lett. 120, 106802] Published Fri Mar 09, 2018

]]>We predict a strong enhancement of the critical temperature in a conventional Bardeen-Cooper-Schrieffer (BCS) superconductor in the presence of a bosonic condensate of exciton polaritons. The effect depends strongly on the ratio of the cutoff frequencies for phonon and exciton-polariton mediated BCS...

[Phys. Rev. Lett. 120, 107001] Published Fri Mar 09, 2018

]]>We address the question about the origin of the $\frac{1}{2}({e}^{2}/h)$ conductance plateau observed in a recent experiment on an integer quantum Hall (IQH) film covered by a superconducting (SC) film. Since one-dimensional (1D) chiral Majorana fermions on the edge of the above device can give rise to the half qua...

[Phys. Rev. Lett. 120, 107002] Published Fri Mar 09, 2018

]]>We exploit an intense terahertz magnetic near field combined with femtosecond laser excitation to break the symmetry of photoinduced spin reorientation paths in ${\mathrm{ErFeO}}_{3}$. We succeed in aligning macroscopic magnetization reaching up to 80% of total magnetization in the sample to selectable orientations...

[Phys. Rev. Lett. 120, 107202] Published Fri Mar 09, 2018

]]>We investigated the ultrafast terahertz (THz) nonlinearity in a monolayer graphene under the strong magnetic field using THz pump-THz probe spectroscopy. An ultrafast suppression of the Faraday rotation associated with inter-Landau level (LL) transitions is observed, reflecting the Dirac electron ch...

[Phys. Rev. Lett. 120, 107401] Published Fri Mar 09, 2018

]]>A theory is developed for the emission noise at frequency $\nu $ in a quantum dot in the presence of Coulomb interactions and asymmetric couplings to the reservoirs. We give an analytical expression for the noise in terms of the various transmission amplitudes. Including the inelastic scattering contribu...

[Phys. Rev. Lett. 120, 107702] Published Fri Mar 09, 2018

]]>The valence band maximum in transition metal dicalcogenides is tuned by applying a transverse electric field to the material.

[Phys. Rev. Lett. 120, 107703] Published Fri Mar 09, 2018

]]>When a $d$-dimensional quantum system is subjected to a periodic drive, it may be treated as a ($d+1$)-dimensional system, where the extra dimension is a synthetic one. This approach, however, affords only a limited level of control of the effective potential along the synthetic direction. In this work,...

[Phys. Rev. Lett. 120, 106402] Published Thu Mar 08, 2018

]]>We study chemically gated bilayer graphene using scanning tunneling microscopy and spectroscopy complemented by tight-binding calculations. Gating is achieved by intercalating Cs between bilayer graphene and Ir(111), thereby shifting the conduction band minima below the chemical potential. Scatterin...

[Phys. Rev. Lett. 120, 106801] Published Thu Mar 08, 2018

]]>The absence of the negative sign problem in quantum Monte Carlo simulations of spin and fermion systems has different origins. World-line based algorithms for spins require positivity of matrix elements whereas auxiliary field approaches for fermions depend on symmetries such as particle-hole symmet...

[Phys. Rev. Lett. 120, 107201] Published Thu Mar 08, 2018

]]>van der Waals heterostructures (VDWHs) exhibit rich properties and thus has potential for applications, and charge transfer between different layers in a heterostructure often dominates its properties and device performance. It is thus critical to reveal and understand the charge transfer effects in...

[Phys. Rev. Lett. 120, 106401] Published Wed Mar 07, 2018

]]>We develop a Landauer-Büttiker theory of entropy evolution in time-dependent, strongly coupled electron systems. The formalism naturally avoids the problem of the system-bath distinction by defining the entropy current in the attached leads. This current can then be used to infer changes of the entr...

[Phys. Rev. Lett. 120, 107701] Published Mon Mar 05, 2018

]]>We study the impact of quenched disorder (random exchange couplings or site dilution) on easy-plane pyrochlore antiferromagnets. In the clean system, order by disorder selects a magnetically ordered state from a classically degenerate manifold. In the presence of randomness, however, different order...

[Phys. Rev. Lett. 120, 097204] Published Fri Mar 02, 2018

]]>Three new transistors for spin-based currents may lead to a new type of circuitry that is faster and more efficient than traditional electronics.

[Phys. Rev. Lett. 120, 097205] Published Fri Mar 02, 2018

]]>We study exciton polaritons in a two-dimensional Lieb lattice of micropillars. The energy spectrum of the system features two flat bands formed from $S$ and ${P}_{x,y}$ photonic orbitals, into which we trigger bosonic condensation under high power excitation. The symmetry of the orbital wave functions combin...

[Phys. Rev. Lett. 120, 097401] Published Fri Mar 02, 2018

]]>Three new transistors for spin-based currents may lead to a new type of circuitry that is faster and more efficient than traditional electronics.

[Phys. Rev. Lett. 120, 097702] Published Fri Mar 02, 2018

]]>Robust spin Hall effects (SHE) have recently been observed in nonmagnetic heavy metal systems with strong spin-orbit interactions. These SHE are either attributed to an intrinsic band-structure effect or to extrinsic spin-dependent scattering from impurities, namely, side jump or skew scattering. He...

[Phys. Rev. Lett. 120, 097203] Published Thu Mar 01, 2018

]]>Understanding the interplay between the topological nature and the symmetry property of interacting systems has been a central matter of condensed matter physics in recent years. In this Letter, we establish nonperturbative constraints on the quantized Hall conductance of many-body systems with arbi...

[Phys. Rev. Lett. 120, 096601] Published Wed Feb 28, 2018

]]>As the Fermi level and band structure of two-dimensional materials are readily tunable, they constitute an ideal platform for exploring the Lifshitz transition, a change in the topology of a material’s Fermi surface. Using tetralayer graphene that host two intersecting massive Dirac bands, we demons...

[Phys. Rev. Lett. 120, 096802] Published Wed Feb 28, 2018

]]>We report the discovery of a field driven transition from a single-$q$ to multi-$q$ spin density wave (SDW) in the tetragonal heavy fermion compound ${\mathrm{CeAuSb}}_{2}$. Polarized along $\mathbf{c}$, the sinusoidal SDW amplitude is $1.8(2){\mu}_{B}/\mathrm{Ce}$ for $T\ll {T}_{N}=6.25(10)\text{\hspace{0.17em}}\text{\hspace{0.17em}}\mathrm{K}$ with a wave vector ${\mathbf{q}}_{1}=(\eta ,\eta ,1/2)$ $[\eta =0.136(2)]$. For $\mathbf{H}\parallel \mathbf{c}$, harmoni...

[Phys. Rev. Lett. 120, 097201] Published Wed Feb 28, 2018

]]>Magnetocrystalline anisotropy, the microscopic origin of permanent magnetism, is often explained in terms of ferromagnets. However, the best performing permanent magnets based on rare earths and transition metals (RE-TM) are in fact *ferri*magnets, consisting of a number of magnetic sublattices. Here ...

[Phys. Rev. Lett. 120, 097202] Published Wed Feb 28, 2018

]]>Crystal structures and the Bloch theorem play a fundamental role in condensed matter physics. We extend the static crystal to the dynamic “space-time” crystal characterized by the general intertwined space-time periodicities in $D+1$ dimensions, which include both the static crystal and the Floquet cr...

[Phys. Rev. Lett. 120, 096401] Published Tue Feb 27, 2018

]]>The ground state of nanowires of single-crystalline pyrochlore ${\mathrm{Y}}_{2}{\mathrm{Ir}}_{2}{\mathrm{O}}_{7}$ is a density wave. The application of a *transverse* magnetic field increases the threshold electric field for the collective depinning of the density wave state at a low temperature, leading to colossal magnetoresistance for volta...

[Phys. Rev. Lett. 120, 096801] Published Tue Feb 27, 2018

]]>Single monolayer FeSe film grown on a Nb-doped ${\mathrm{SrTiO}}_{3}(001)$ substrate shows the highest superconducting transition temperature (${T}_{C}\sim 100\text{\hspace{0.17em}}\text{\hspace{0.17em}}\mathrm{K}$) among the iron-based superconductors (iron pnictides), while the ${T}_{C}$ value of bulk FeSe is only $\sim 8\text{\hspace{0.17em}}\text{\hspace{0.17em}}\mathrm{K}$. Although bulk FeSe does not show antiferromagnetic order, ca...

[Phys. Rev. Lett. 120, 097001] Published Tue Feb 27, 2018

]]>Researchers use a cavity-coupled double quantum dot to study electron-phonon interactions in a nanowire.

[Phys. Rev. Lett. 120, 097701] Published Tue Feb 27, 2018

]]>Recent experiments have explored two-dimensional electron gases (2DEGs) at oxide (111) surfaces and interfaces, finding evidence for hexagonal symmetry breaking in ${\mathrm{SrTiO}}_{3}$ at low temperature. We discuss many-body instabilities of such (111) 2DEGs, incorporating multiorbital interactions in the ${t}_{2g}$ ma...

[Phys. Rev. Lett. 120, 086802] Published Fri Feb 23, 2018

]]>We report the first determination of the in-plane complex optical conductivity of 1111 high-${T}_{c}$ superconducting iron oxypnictide single crystals PrFeAs(O,F) and thin films SmFeAs(O,F) by means of conventional and microfocused infrared spectroscopy, ellipsometry, and time-domain THz transmission spect...

[Phys. Rev. Lett. 120, 087001] Published Fri Feb 23, 2018

]]>We show that band topology can dramatically change the photophysics of two-dimensional semiconductors. For systems in which states near the band extrema are of multicomponent character, the spinors describing these components (pseudospins) can pick up nonzero winding numbers around the extremal $k$ po...

[Phys. Rev. Lett. 120, 087402] Published Fri Feb 23, 2018

]]>The visualization of the Landau levels in HgTe/CdTe quantum wells at different temperatures allows the exploration of the phase diagram as a function of magnetic field and temperature.

[Phys. Rev. Lett. 120, 086401] Published Thu Feb 22, 2018

]]>Hyperfine interaction (HFI), originating from the coupling between spins of charge carriers and nuclei, has been demonstrated to strongly influence the spin dynamics of localized charges in organic semiconductors. Nevertheless, the role of charge localization on the HFI strength in organic thin film...

[Phys. Rev. Lett. 120, 086602] Published Thu Feb 22, 2018

]]>Topological phases of fermions in two dimensions are often characterized by chiral edge states. By definition, these propagate in opposite directions at the two parallel edges when the sample geometry is that of a rectangular strip. We introduce here a model which exhibits what we call “antichiral” ...

[Phys. Rev. Lett. 120, 086603] Published Thu Feb 22, 2018

]]>We report on comprehensive results identifying the ground state of a triangular-lattice structured ${\mathrm{YbZnGaO}}_{4}$ as a spin glass, including no long-range magnetic order, prominent broad excitation continua, and the absence of magnetic thermal conductivity. More crucially, from the ultralow-temperature ac...

[Phys. Rev. Lett. 120, 087201] Published Thu Feb 22, 2018

]]>We explore the unconventional wave scattering properties of non-Hermitian systems in which amplification or damping are induced by time-periodic modulation. These non-Hermitian time-Floquet systems are capable of nonreciprocal operations in the frequency domain, which can be exploited to induce nove...

[Phys. Rev. Lett. 120, 087401] Published Thu Feb 22, 2018

]]>Electron waiting times are an important concept in the analysis of quantum transport in nanoscale conductors. Here we show that the statistics of electron waiting times can be used to characterize Cooper pair splitters that create spatially separated spin-entangled electrons. A short waiting time be...

[Phys. Rev. Lett. 120, 087701] Published Thu Feb 22, 2018

]]>Experimental determinations of bulk band topology in the solid states have been so far restricted to only indirect investigation through the probing of surface states predicted by electronic structure calculations. We here present an alternative approach to determine the band topology by means of bu...

[Phys. Rev. Lett. 120, 086402] Published Wed Feb 21, 2018

]]>The crystal axes of an arbitrarily-shaped, exfoliated semiconductor flake are determined via resistivity measurements.

[Phys. Rev. Lett. 120, 086801] Published Wed Feb 21, 2018

]]>We develop the quantum hydrodynamics of inner waves in the bulk of fractional quantum Hall states. We show that the inelastic light scattering by inner waves is a sole effect of the gravitational anomaly. We obtain the formula for the oscillator strength or mean energy of optical absorption expresse...

[Phys. Rev. Lett. 120, 086601] Published Tue Feb 20, 2018

]]>Our analysis of the contact formation processes undergone by Au, Ag, and Cu nanojunctions reveals that the distance at which the two closest atoms on a pair of opposing electrodes jump into contact is, on average, 2 times longer for Au than either Ag or Cu. This suggests the existence of a longer-ra...

[Phys. Rev. Lett. 120, 076802] Published Fri Feb 16, 2018

]]>We propose a trial wave function for the quantum Hall bilayer system of total filling factor ${\nu}_{T}=1$ at a layer distance $d$ to magnetic length $\ell $ ratio $d/\ell ={\kappa}_{c1}\approx 1.1$, where the lowest charged excitation is known to have a level crossing. The wave function has two-particle correlations, which fit well with ...

[Phys. Rev. Lett. 120, 077601] Published Fri Feb 16, 2018

]]>We report on short ballistic (SB) Josephson coupling in junctions embedded in a planar heterostructure of graphene. Ballistic Josephson coupling is confirmed by the Fabry-Perot-type interference of the junction critical current ${I}_{c}$. The product of ${I}_{c}$ and the normal-state junction resistance ${R}_{N}$, norma...

[Phys. Rev. Lett. 120, 077701] Published Fri Feb 16, 2018

]]>Recent studies have brought $\alpha \text{\u2212}{\mathrm{RuCl}}_{3}$ to the forefront of experimental searches for materials realizing Kitaev spin-liquid physics. This material exhibits strongly anisotropic exchange interactions afforded by the spin-orbit coupling of the $4d$ Ru centers. We investigate the dynamical response at finit...

[Phys. Rev. Lett. 120, 077203] Published Thu Feb 15, 2018

]]>We show that the exciton optical selection rule in gapped chiral fermion systems is governed by their winding number $w$, a topological quantity of the Bloch bands. Specifically, in a ${C}_{N}$-invariant chiral fermion system, the angular momentum of bright exciton states is given by $w\pm 1+nN$ with $n$ being an i...

[Phys. Rev. Lett. 120, 077401] Published Thu Feb 15, 2018

]]>Realizing the potential for predictive density functional calculations of matter under extreme conditions depends crucially upon having an exchange-correlation ($XC$) free-energy functional accurate over a wide range of state conditions. Unlike the ground-state case, no such functional exists. We reme...

[Phys. Rev. Lett. 120, 076401] Published Wed Feb 14, 2018

]]>In Dirac materials linear band dispersion blocks momentum-conserving interband transitions, creating a bottleneck for electron-hole pair production and carrier multiplication in the photoexcitation cascade. Here we show that the decays are unblocked and the bottleneck is relieved by subtle many-body...

[Phys. Rev. Lett. 120, 076601] Published Wed Feb 14, 2018

]]>We report the results of a combined study of the normal-state resistivity and superconducting transition temperature ${T}_{c}$ of the unconventional superconductor ${\mathrm{Sr}}_{2}{\mathrm{RuO}}_{4}$ under uniaxial pressure. There is strong evidence that, as well as driving ${T}_{c}$ through a maximum at $\sim 3.5\text{\hspace{0.17em}}\text{\hspace{0.17em}}\mathrm{K}$, compressive strains $\u03f5$ of ne...

[Phys. Rev. Lett. 120, 076602] Published Wed Feb 14, 2018

]]>The widely reported magnetoresistance oscillations in ${\mathrm{LaAlO}}_{3}/{\mathrm{SrTiO}}_{3}$ heterostructures have invariably been attributed to the Shubnikov–de Haas (SdH) effect, despite a pronounced inconsistency with low-field Hall resistance measurements. Here we report SdH-like resistance oscillations in quasi-1D elec...

[Phys. Rev. Lett. 120, 076801] Published Wed Feb 14, 2018

]]>Skyrmions are disklike objects that typically form triangular crystals in two-dimensional systems. This situation is analogous to the so-called pancake vortices of quasi-two-dimensional superconductors. The way in which Skyrmion disks or “pancake Skyrmions” pile up in layered centrosymmetric materia...

[Phys. Rev. Lett. 120, 077202] Published Tue Feb 13, 2018

]]>A functional design for the cluster-based $S$=1 Haldane state is proposed and confirmed experimentally in an edge-shared tetrahedral spin-cluster chain system.

[Phys. Rev. Lett. 120, 077201] Published Mon Feb 12, 2018

]]>A key issue in heavy fermion research is how subtle changes in the hybridization between the $4f$ ($5f$) and conduction electrons can result in fundamentally different ground states. ${\mathrm{CeRhIn}}_{5}$ stands out as a particularly notable example: when replacing Rh with either Co or Ir, antiferromagnetism gives wa...

[Phys. Rev. Lett. 120, 066403] Published Fri Feb 09, 2018

]]>We study the relationship between the pseudogap and Fermi-surface topology in the two-dimensional Hubbard model by means of the cellular dynamical mean-field theory. We find two possible mean-field metallic solutions on a broad range of interactions, doping, and frustration: a conventional renormali...

[Phys. Rev. Lett. 120, 067002] Published Fri Feb 09, 2018

]]>We generalize the concept of Berry connection of the single-electron band structure to that of a two-particle Cooper pairing state between two Fermi surfaces with opposite Chern numbers. Because of underlying Fermi surface topology, the pairing Berry phase acquires nontrivial monopole structure. Con...

[Phys. Rev. Lett. 120, 067003] Published Fri Feb 09, 2018

]]>We utilize nanoscale spin valves with Pt spacer layers to characterize spin relaxation in Pt. Analysis of the spin lifetime indicates that Elliott-Yafet spin scattering is dominant at room temperature, but an unexpected intrinsic Dyakonov-Perel-like spin relaxation becomes dominant at cryogenic temp...

[Phys. Rev. Lett. 120, 067204] Published Fri Feb 09, 2018

]]>We measure the doping dependence of the valley Zeeman splitting of the fundamental optical transitions in monolayer ${\mathrm{WSe}}_{2}$ under an out-of-plane magnetic field by optical reflection contrast and photoluminescence spectroscopy. A nonlinear valley Zeeman effect, correlated with an over fourfold enhancem...

[Phys. Rev. Lett. 120, 066402] Published Thu Feb 08, 2018

]]>Typically, the chiral magnetic Skyrmion is a single-state excitation. Here we propose a system, where multiplet of Skyrmion states appears and one of these states can be the ground one. We show that the presence of a localized curvilinear defect drastically changes the magnetic properties of a thin ...

[Phys. Rev. Lett. 120, 067201] Published Thu Feb 08, 2018

]]>Recently, there have been increasingly hot debates on whether there exists a quantum spin liquid in the Kitaev honeycomb magnet $\alpha $-${\mathrm{RuCl}}_{3}$ in a high magnetic field. To investigate this issue, we perform ultralow-temperature thermal conductivity measurements on single crystals of $\alpha $-${\mathrm{RuCl}}_{3}$ down to 80 mK a...

[Phys. Rev. Lett. 120, 067202] Published Thu Feb 08, 2018

]]>The mineral linarite, ${\mathrm{PbCuSO}}_{4}(\mathrm{OH}{)}_{2}$, is a spin-$1/2$ chain with frustrating nearest-neighbor ferromagnetic and next-nearest-neighbor antiferromagnetic exchange interactions. Our inelastic neutron scattering experiments performed above the saturation field establish that the ratio between these exchange...

[Phys. Rev. Lett. 120, 067203] Published Thu Feb 08, 2018

]]>Second-harmonic generation is used experimentally for the nonlinear imaging of two-dimensional irregular domain structures. Analytical solutions and simulation results for the Fresnel distribution of domain walls are obtained. The results show that the domain wall plays an important role in the imag...

[Phys. Rev. Lett. 120, 067601] Published Thu Feb 08, 2018

]]>Machine learning trains neural networks to distinguish between different phases in topological band insulators.

[Phys. Rev. Lett. 120, 066401] Published Tue Feb 06, 2018

]]>Josephson current provides a phase-sensitive tool for probing the pairing symmetry. Here we present an experimental study of high-quality Josephson junctions between a conventional $s$-wave superconductor Nb and a multiband iron-pnictide ${\mathrm{Ba}}_{1-x}{\mathrm{Na}}_{x}{\mathrm{Fe}}_{2}{\mathrm{As}}_{2}$. Junctions exhibit a large enough critical curren...

[Phys. Rev. Lett. 120, 067001] Published Tue Feb 06, 2018

]]>A Fibonacci topological superconductor could be realized in a system of interacting Majorana fermions.

[Phys. Rev. Lett. 120, 066801] Published Mon Feb 05, 2018

]]>Anderson localization of light is traditionally described in analogy to electrons in a random potential. Within this description, the random potential depends on the wavelength of the incident light. For transverse Anderson localization, this leads to the prediction that the distribution of localiza...

[Phys. Rev. Lett. 120, 067401] Published Mon Feb 05, 2018

]]>Magnetotransport measurements in combination with molecular dynamics simulations on two-dimensional disordered Lorentz gases in the classical regime are reported. In quantitative agreement between experiment and simulation, the magnetoconductivity displays a pronounced peak as a function of the perp...

[Phys. Rev. Lett. 120, 056601] Published Fri Feb 02, 2018

]]>We investigate unconventional superconductivity in three-dimensional electronic systems with the chemical potential close to a quadratic band touching point in the band dispersion. Short-range interactions can lead to $d$-wave superconductivity, described by a complex tensor order parameter. We elucid...

[Phys. Rev. Lett. 120, 057002] Published Thu Feb 01, 2018

]]>The determination of the band gap and exciton energies of lead halide perovskites is very important from the viewpoint of fundamental physics and photonic device applications. By using photoluminescence excitation (PLE) spectra, we reveal the optical properties of ${\mathrm{CH}}_{3}{\mathrm{NH}}_{3}{\mathrm{PbCl}}_{3}$ single crystals in the ...

[Phys. Rev. Lett. 120, 057404] Published Thu Feb 01, 2018

]]>Magnetic-field-dependent magnetoabsorption measurements of Rydberg excitons in a monolayer dichalcogenide semiconductor allow benchmarking of theories of the nonhydrogenic Coulomb potential believed to describe atomically thin materials.

[Phys. Rev. Lett. 120, 057405] Published Thu Feb 01, 2018

]]>The topological magnetoelectric effect is observed in a heterostructure of magnetic and nonmagnetic topological insulators.

[Phys. Rev. Lett. 120, 056801] Published Wed Jan 31, 2018

]]>We show that topology can protect exponentially localized, zero energy edge modes at critical points between one-dimensional symmetry-protected topological phases. This is possible even without gapped degrees of freedom in the bulk—in contrast to recent work on edge modes in gapless chains. We prese...

[Phys. Rev. Lett. 120, 057001] Published Wed Jan 31, 2018

]]>We present a multiloop flow equation for the four-point vertex in the functional renormalization group (FRG) framework. The multiloop flow consists of successive one-loop calculations and sums up all parquet diagrams to arbitrary order. This provides substantial improvement of FRG computations for t...

[Phys. Rev. Lett. 120, 057403] Published Wed Jan 31, 2018

]]>The edge states of the quantum Hall and fractional quantum Hall effect of a two-dimensional electron gas carry key information of the bulk excitations. Here we demonstrate gate-controlled transmission of edge states in bilayer graphene through a potential barrier with tunable height. The backscatter...

[Phys. Rev. Lett. 120, 057701] Published Wed Jan 31, 2018

]]>We report the first observation of the magnon-polariton bistability in a cavity magnonics system consisting of cavity photons strongly interacting with the magnons in a small yttrium iron garnet (YIG) sphere. The bistable behaviors emerged as sharp frequency switchings of the cavity magnon polariton...

[Phys. Rev. Lett. 120, 057202] Published Tue Jan 30, 2018

]]>Quantum Hall polaritons in the strong coupling regime are studied experimentally in GaAs. These polaritons are expected to be useful in implementing a photonic quantum simulator.

[Phys. Rev. Lett. 120, 057401] Published Tue Jan 30, 2018

]]>The recent claim of having produced metallic hydrogen in the laboratory relies on measurements of optical spectra. Here, we present first-principles calculations of the reflectivity of hydrogen between 400 and 600 GPa in the $I{4}_{1}/amd$ crystal structure, the one predicted at these pressures, based on b...

[Phys. Rev. Lett. 120, 057402] Published Tue Jan 30, 2018

]]>Motivated by the recent synthesis of the spin-1 $A$-site spinel ${\mathrm{NiRh}}_{2}{\mathrm{O}}_{4}$, we investigate the classical to quantum crossover of a frustrated ${J}_{1}\text{\u2212}{J}_{2}$ Heisenberg model on the diamond lattice upon varying the spin length $S$. Applying a recently developed pseudospin functional renormalization group approach fo...

[Phys. Rev. Lett. 120, 057201] Published Mon Jan 29, 2018

]]>We demonstrate simultaneous quantization of conduction band (CB) and valence band (VB) states in silicon using ultrashallow, high-density, phosphorus doping profiles (so-called Si:P $\delta $ layers). We show that, in addition to the well-known quantization of CB states within the dopant plane, the confinem...

[Phys. Rev. Lett. 120, 046403] Published Fri Jan 26, 2018

]]>The polarization dependence of the photoconductivity response at cyclotron-resonance harmonics in a nondegenerate two-dimensional (2D) electron system formed on the surface of liquid helium is studied using a setup in which a circular polarization of opposite directions can be produced. Contrary to ...

[Phys. Rev. Lett. 120, 046802] Published Fri Jan 26, 2018

]]>We study the exciton gas-liquid transition in $\mathrm{GaAs}/\mathrm{AlGaAs}$ coupled quantum wells. Below a critical temperature, ${T}_{C}=4.8\text{\hspace{0.17em}}\text{\hspace{0.17em}}\mathrm{K}$, and above a threshold laser power density the system undergoes a phase transition into a liquid state. We determine the density-temperature phase diagram over the temperature ran...

[Phys. Rev. Lett. 120, 047402] Published Fri Jan 26, 2018

]]>The $E=0$ octet of bilayer graphene in the filling factor range of $-4<\nu <4$ is a fertile playground for many-body phenomena, yet a Landau level diagram is missing due to strong interactions and competing quantum degrees of freedom. We combine measurements and modeling to construct an empirical and...

[Phys. Rev. Lett. 120, 047701] Published Fri Jan 26, 2018

]]>Josephson junctions defined in strong spin orbit semiconductors are highly interesting for the search for topological systems. However, next to topological edge states that emerge in a sufficient magnetic field, trivial edge states can also occur. We study the trivial edge states with superconductin...

[Phys. Rev. Lett. 120, 047702] Published Fri Jan 26, 2018

]]>We introduce in this Letter an exact solvable BCS-Hubbard model in arbitrary dimensions. The model describes a $p$-wave BCS superconductor with equal spin pairing moving on a bipartite (cubic, square, etc.) lattice with on-site Hubbard interaction $U$. We show that the model becomes exactly solvable for...

[Phys. Rev. Lett. 120, 046401] Published Thu Jan 25, 2018

]]>We report the experimental observation of $2s$ exciton radiative emission from monolayer tungsten diselenide, enabled by hexagonal boron nitride protected high-quality samples. The $2s$ luminescence is highly robust and persists up to 150 K, offering a new quantum entity for manipulating the valley degr...

[Phys. Rev. Lett. 120, 046402] Published Thu Jan 25, 2018

]]>We present an effective (minimal) theory for chiral two-dimensional materials. These materials possess an electromagnetic coupling without exhibiting a topological gap. As an example, we study the response of doped twisted bilayers, unveiling unusual phenomena in the zero frequency limit. An in-plan...

[Phys. Rev. Lett. 120, 046801] Published Thu Jan 25, 2018

]]>We study the infrared cyclotron resonance of high-mobility monolayer graphene encapsulated in hexagonal boron nitride, and simultaneously observe several narrow resonance lines due to interband Landau-level transitions. By holding the magnetic field strength $B$ constant while tuning the carrier densi...

[Phys. Rev. Lett. 120, 047401] Published Thu Jan 25, 2018

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