In this work, we propose a way to achieve flexible long-range and large-area electromagnetic (EM) manipulation by using a pair of topological one-way large-area waveguide states (TOLWSs) propagating in the same direction in a photonic crystal ABC heterostructure. Due to the topological protection of TOLWSs, backscattering is forbidden against the local perturbation during their propagation. When one of them is excited, the particle located in the middle B area results in scattering between two copropagating TOLWSs. This mode-conversion effect leads to flexible EM manipulation, i.e., the particle can be pulled or pushed towards or away from the source depending on its frequency and mode. Furthermore, it is also found that the directions of the longitudinal EM force also depend on the constituent materials of the particles, which suggests a particle-sorting mechanism based on TOLWSs. More importantly, as a demonstration of multiparticles' EM simultaneous manipulation via TOLWSs, the EM forces of two and three particles located in the B region are calculated and studied. It is found that both particles can be pulled or pushed at the same time. Our work paves the way for the potentially important application of TOLWSs in EM manipulation, which is expected to be realized in the experiment in the near future.

The ABA-stacked trilayer graphene (TLG) has a parabolic dispersion band spanning the Fermi level, apart from the linear dispersion band which is almost a duplicate of that in monolayer graphene (MLG). Such a band structure implies that the TLG is a metal and seemingly has a larger conductivity than MLG due to the additional contributions of the parabolic bands when the linear dispersion bands in TLG and MLG host the same number of carriers. However, our numerical calculations indicate that the conductivity of TLG is smaller than that in MLG roughly by 20% when a moderate carrier doping drives the Fermi energy away from the Dirac point by at least 50 meV. To explain such a disagreement between the band structure and the conductivity, we find that the out-of-plane atomic vibration, i.e., the so-called $ZA$ phonon mode in the long-wavelength region, plays a critical role in limiting the conductivity of TLG due to the strong interband scattering. In contrast to MLG, such a $ZA$ phonon mode is completely decoupled from the electron-phonon scattering due to the symmetry incompatibility.

Crystalline black nitrogen (BN) is an allotrope of nitrogen with the black phosphorus (BP) structure recently synthesized at high pressure by two independent research groups [Ji et al., Sci. Adv. 6, eaba9206 (2020); Laniel et al., Phys. Rev. Lett. 124, 216001 (2020)]. Here, we present a systematic study of the electronic and optical properties of BN focusing on its comparison with BP. To this end, we use the state-of-the-art quasiparticle self-consistent $GW$ approach with vertex corrections in both the electronic and optical channels. Despite many similarities, the properties of BN are found to be considerably different. Unlike BP, BN exhibits a larger optical gap (2.5 vs 0.26 eV), making BN transparent in the visible spectral region with a highly anisotropic optical response. This difference can be primarily attributed to a considerably reduced dielectric screening in BN, leading to enhancement of the effective Coulomb interaction. Despite relatively strong Coulomb interaction, exciton formation is largely suppressed in both materials. Our analysis of the elastic properties shows exceptionally high stiffness of BN, comparable to that of diamond.

The quasiparticle self-consistent (QS) $\mathit{GW}$ ($G$ for Green's function, $W$ for screened Coulomb interaction) approach incorporates the corrections of the quasiparticle energies from their Kohn-Sham density functional theory (DFT) eigenvalues by means of an energy-independent and Hermitian self-energy matrix usually given in the basis set of the DFT eigenstates. By expanding these into an atom-centered basis set (specifically here the linearized muffin-tin orbitals) a real space representation of the self-energy corrections becomes possible. We show that this representation is relatively short-ranged. This offers opportunities to construct the self-energy of a complex system from parts of the system by a cut-and-paste method. Specifically for a point defect, represented in a large supercell, the self-energy can be constructed from those of the host and a smaller defect-containing cell. The self-energy of the periodic host can be constructed simply from a $GW$ calculation for the primitive cell. We show for the case of the ${\mathrm{As}}_{\mathrm{Ga}}$ in GaAs that the defect part can already be well represented by a minimal eight-atom cell and allows us to construct the self-energy for a 64-atom cell in good agreement with direct $\mathrm{QS}GW$ calculations for the large cell. Using this approach to an even larger 216-atom cell shows the defect band approaches an isolated defect level. The calculations also allow us to identify a second defect band which appears as a resonance near the conduction band minimum. The results on the extracted defect levels agree well with Green's function calculations for an isolated defect and with experimental data.

In an Anderson localized system, a quantum particle with a nonzero initial velocity returns, on average, to its origin. This recently discovered behavior is known as the quantum boomerang effect. Time-reversal invariance was initially thought to be a necessary condition for the existence of this phenomenon. We theoretically analyze the impact of the symmetry breaking on the phenomenon using a one-dimensional system with a spin-orbit coupling and show that the time-reversal invariance is not necessary for the boomerang effect to occur. We explain this behavior giving sufficient symmetry conditions for the boomerang effect to occur when time-reversal symmetry is broken.

We investigate the low-temperature properties of the Ising-like screw chain antiferromagnet ${\mathrm{SrCo}}_2{\mathrm{V}}_2{\mathrm{O}}_8$ under a longitudinal magnetic field by susceptibility and ${}^{51}\mathrm{V}$ NMR measurements. The bulk susceptibility $\chi$ shows an onset of long-range Ising-antiferromagnetic (AFM) order and the suppression of the order by field with the Néel temperature dropped from 5.1 to 2 K when field increases from 0.1 to 4 T. The suppression of the AFM order by the field is also observed by the NMR spectra and the spin-lattice relaxation $1/T_1$. At fields above 4 T, $\chi$ shows a low-temperature upturn, which is consistent with the onset of a transverse antiferromagnetic order as supported by the quantum Monte Carlo simulations. A line splitting in the NMR spectra is also observed at high temperatures. We show that the line split characterizes the onset of a short-range transverse antiferromagnetic order with magnetic moments orientated along the crystalline $\left[110\right]/\left[1\overline{1}0\right]$ directions. The $1/T_1$ data at higher temperature show a power-law behavior $1/T_1\sim T^{\alpha }$, which is consistent with the Tomonaga-Luttinger-liquid behavior. With increasing the field, the power-law exponent $\alpha$ changes from negative to positive, which clearly shows an inversion of the Luttinger exponent $\eta$ where the dominant low-energy spin fluctuations switch from the longitudinal type to the transverse type at a high field of 7 T.

Magnetically hidden order is a hypernym for electronic ordering phenomena that are visible to macroscopic thermodynamic probes but whose microscopic symmetry cannot be revealed with conventional neutron or x-ray diffraction. In a handful of $f$-electron systems, the ordering of odd-rank multipoles leads to order parameters with a vanishing neutron cross section. Among them, ${\mathrm{Ce}}_3{\mathrm{Pd}}_{20}{\mathrm{Si}}_6$ is known for its unique phase diagram exhibiting two distinct multipolar-ordered ground states (phases II and ${\mathrm{II}}^{\prime }$), separated by a field-driven quantum phase transition associated with a putative change in the ordered quadrupolar moment from $O_2^0$ to $O_{xy}$. Using torque magnetometry at sub-kelvin temperatures, here we find another phase transition at higher fields above 12 T, which appears only for low-symmetry magnetic field directions $\mathbf{B}\parallel \langle 11L\rangle$ with $1<L\le 2$. While the order parameter of this new phase ${\mathrm{II}}^{\prime \prime }$ remains unknown, the discovery renders ${\mathrm{Ce}}_3{\mathrm{Pd}}_{20}{\mathrm{Si}}_6$ a unique material with two field-driven phase transitions between distinct multipolar phases. They are both clearly manifested in the magnetic-field dependence of the field-induced (111) Bragg intensities measured with neutron scattering for $\mathbf{B}\parallel \left[11\overline{2}\right]$. We also find from inelastic neutron scattering that the number of nondegenerate collective excitations induced by the magnetic field correlates with the number of phases in the magnetic phase diagram for the same field direction. Furthermore, the magnetic excitation spectrum suggests that the new phase ${\mathrm{II}}^{\prime \prime }$ may have a different propagation vector, revealed by the minimum in the dispersion that may represent the Goldstone mode of this hidden-order phase.

Doping represents one of the most promising avenues for optimizing superconductors, such as high-pressure conventional superconductors with record-breaking critical temperatures. In this work, we perform an extensive search for substitutional dopants in ${\mathrm{LaH}}_{10}$, looking for elements that enhance its electronic structure. In total, 70 elements were investigated as possible substitutions of La-sites at doping ratio of 12.5% under high pressure. To accelerate the screening of the ternary phases, our protocol to scan the chemical space is 1) to be constrained to highly symmetric patterns of hydrogen atoms, 2) focusing on phases with compact basis of lanthanum atoms (minimize enthalpy) and 3) to choose candidate dopants that preserve the van Hove singularity around the Fermi level. We found Ca as the best candidate dopants, which shift the van Hove singularity and increase the electronic DOS at the Fermi level. By using harmonic-level phonon calculations and performing first-principles calculation of $T_{\mathrm{c}}$, Ca-doped ${\mathrm{LaH}}_{10}$ shows $T_{\mathrm{c}}$ which is 15% higher than the one of ${\mathrm{LaH}}_{10}$. It provides a promising route to reach room-temperature superconductivity in pressurized hydrides by doping.

We re-examine the problem of a magnetic impurity coupled to a superconductor focusing on the role of quantum fluctuations. We study in detail a system that consists of a one-dimensional charge conserving spin-singlet superconductor coupled to a boundary magnetic impurity. Our main finding is that quantum fluctuations lead to the destruction of Yu-Shiba-Rusinov (YSR) intragap bound states in all but a narrow region of the phase diagram. We carry out our analysis in three stages, increasing the role of the quantum fluctuations at each stage. First we consider the limit of a classical impurity and study the bulk semiclassically, finding YSR states throughout the phase diagram, a situation similar to conventional BCS superconductors. In the second stage, we reintroduce quantum fluctuations in the bulk and find that the YSR state is suppressed over half of the phase diagram, existing only around the quantum critical point separating the unscreened and the partially screened phases. In the final stage we solve exactly the full interacting model with arbitrary coupling constants using the Bethe ansatz. We find that including both the quantum fluctuating bulk and quantum impurity destabilizes the YSR state over most of the phase diagram allowing it to exist only in a small region, the YSR regime, between a Kondo-screened and an unscreened regime. Within the YSR regime a first-order phase transition occurs between a spin singlet and doublet ground state. We also find that for large-enough impurity spin exchange interaction a renormalized Kondo-screened regime is established. In this regime, not found for BCS superconductors, there is no YSR state and a renormalized Kondo temperature scale is generated.

We experimentally determine the lattice dynamics of black phosphorus layered crystals through a combination of x-ray diffuse scattering and inelastic x-ray scattering, and we rationalize our experimental findings using ab initio calculations. From the phonon dispersions, at terahertz frequencies, we derive the full single-crystal elastic tensor and relate it to the macroscopic elastic response of black phosphorus, described by the elastic moduli. The elastic stiffness coefficients obtained here provide an important benchmark for models of black phosphorus and related materials, such as phosphorene and black phosphorus nanotubes, recently emerged quantum materials, disclosing a huge potential for nanophotonics, optoelectronics, and quantum sensing.

We predict a spin anomalous-Hall unidirectional magnetoresistance (AH-UMR) in conducting bilayers composed of a ferromagnetic layer and a nonmagnetic layer, which does not rely on the spin Hall effect in the normal metal layer—in stark contrast to the well-studied unidirectional spin-Hall magnetoresistance—but instead arises from the spin anomalous Hall effect in the ferromagnetic layer. Physically, it is the charge-spin conversion induced by the spin anomalous Hall effect that conspires with the structural inversion asymmetry to generate a net nonequilibrium spin density in the ferromagnetic layer, which, in turn, modulates the resistance of the bilayer when the direction of the applied current or the magnetization is reversed. The dependencies of the spin AH-UMR effect on materials and geometric parameters are analyzed and compared with other nonlinear magnetoresistances. In particular, we show that, in magnetic bilayers where spin anomalous Hall and spin Hall effects are comparable, the overall UMR may undergo a sign change when the thickness of either layer is varied, suggesting a scheme to quantify the spin Hall or spin anomalous Hall angle via a nonlinear transport measurement.

Is it possible to readily distinguish a system made by an Avogadro's number of identical elements and one with a single additional one? Usually, the answer to this question is negative but, in this work, we show that in antiferromagnetic quantum spin rings a simple out-of-equilibrium experiment can do so, yielding two qualitatively and quantitatively different outcomes depending on whether the system includes an even or an odd number of elements. We consider a local quantum-quench setup and calculate a generating function of the work done, namely, the Loschmidt echo, showing that it displays different features depending on the presence or absence of topological frustration, which is triggered by the even/oddness in the number of the chain sites. We employ the prototypical quantum Ising chain to illustrate this phenomenology, which we argue being generic for antiferromagnetic spin chains, as it stems primarily from the different low energy spectra of frustrated and nonfrustrated chains. Our results thus prove that these well-known spectral differences lead indeed to distinct observable characteristics and open the way to harvest them in quantum thermodynamics protocols.

We report the crystal growth and structural and electronic properties of superconducting, van der Waals layered PtTe. Easily cleavable crystals with a platelike morphology consistent with the layered structure were grown from a platinum-rich flux. A consistent determination of $T_c=0.57$ K is made from the onset of diamagnetism, the zero of resistivity, and the midpoint of the heat-capacity jump. The observed behavior is consistent with type-II superconductivity, with upper critical field at $T=0$ estimated using the Werthamer-Helfand-Hohenberg theory to be 143 and 65 Oe for fields out of and in the plane, respectively. The heat-capacity discontinuity is close to the weak-coupling BCS value. Density-functional theory calculations and analysis of the electronic structure finds that PtTe is a topological semimetal with numerous surface states but suggests that the superconducting state itself may be topologically trivial. Angle-resolved photoemission spectroscopy reveals a normal-state Fermi surface in remarkable agreement with theory and confirms the overall topological nature of the material by experimental identification of the surface bands. Together, these findings identify PtTe as an interesting example of a cleavable, topological, and superconducting material.

Doped lead-free halide perovskites have been widely reported for impressive photoluminescence properties. Herein we study the mechanisms of photoluminescence in ${\mathrm{Se}}^{4+}$-, ${\mathrm{Te}}^{4+}$-, ${\mathrm{Sb}}^{3+}$-, and ${\mathrm{Bi}}^{3+}$-doped ${\mathrm{Cs}}_2{\mathrm{ZrCl}}_6$ and also in this undoped host via first-principles calculations with hybrid density functionals. The results show that the main photoluminescence in the host, as well as isovalent and aliovalent dopants, can be attributed to highly localized self-trapped excitons composed of an electron on Zr and a $V_k$ center (molecular-like ${\mathrm{Cl}}_2^{-}$), $M{\mathrm{Cl}}_6$ ($M={\mathrm{Se}}^{4+},{\mathrm{Te}}^{4+}$), and $M{\mathrm{Cl}}_5$ ($M={\mathrm{Bi}}^{3+},{\mathrm{Sb}}^{3+}$) complexes, respectively. The systematic underestimation of the emission energies is discussed and is attributed to the over-relaxation of the excited-state geometric structures. Our results illustrate the photoluminescence processes and excited-state dynamics in host and aliovalent dopant of ${\mathrm{Cs}}_2{\mathrm{ZrCl}}_6$, which may inspire further revelations of the mechanisms of photoluminescence of other materials in the tetravalent halide perovskite family.

Multipolar orderings in degenerate orbital systems offer unique opportunities for emergent topological phases. The phase diagram of interacting spinless fermions in a $p$-band diamond lattice at unit filling is first studied to elucidate the essential role of orbital multipolar orderings in the evolution of multifold degenerate band nodes. The free band structure around the Brillouin zone center is described by two quadratic band nodes each with a threefold degeneracy, which are spanned by the bonding and antibonding $p$-orbital multiplets, respectively. Upon switching on interactions, the triply degenerate band node is split into a pair of Weyl fermions with opposite chirality due to the onset of orbital multipolar orderings. Further raising interactions ultimately drives the system into an insulating phase with the orbital quadrupolar ordering. Our study is then generalized to spin-$\frac{1}{2}$ fermions, which has direct relevance with solid-state materials. The system develops full spin polarization through a ferromagnetic transition at tiny interactions, leaving the remaining orbital sector activated. The ensuing transitions take place in the orbital sector as a natural consequence, qualitatively recovering the phase diagram of spinless fermions. Our findings shed light on the realization of emergent fermions with a prospect being a frontier at the confluence of topology, orbital physics, and strong correlation.

A key feature of many-body localization (MBL) is the breaking of ergodicity and consequently the emergence of local memory, revealed as the local preservation of information over time. As memory is necessarily a time-dependent concept, it has been partially captured by a few extant studies of dynamical quantities. However, these quantities suffer from a variety of issues which limit their value as true quantifiers of memory; thus, a fundamental and complete information-theoretic understanding of local memory in the context of MBL remains elusive. We outline these issues in detail and introduce the dynamical Holevo quantity to address them. We find that it shows clear scaling behavior across the MBL transition, and we determine a family of two-parameter scaling Ansätze which capture this behavior. We perform a comprehensive finite-sized scaling analysis to extract the transition point and scaling exponents.