We present a microscopic derivation of the nematic charge-density wave (CDW) formation in cuprate superconductors based on the three-orbital $d\text{−}p$ Hubbard model by introducing the vertex correction (VC) into the charge susceptibility. The CDW instability at $\mathit{q}=({\mathrm{\Delta }}_{\text{FS}},0)$, $(0,{\mathrm{\Delta }}_{\text{FS}})$ appears when the spin fluctuations are strong, due to the strong charge-spin interference represented by the VC. Here, ${\mathrm{\Delta }}_{\text{FS}}$ is the wave number between the neighboring hot spots. The obtained spin-fluctuation-driven CDW is expressed as the “intra-unit-cell orbital order” accompanied by the charge transfer between the neighboring atomic orbitals, which is actually observed by the scanning tunneling microscope measurements. We predict that the cuprate CDW and the nematic orbital order in Fe-based superconductors are closely related spin-fluctuation-driven phenomena.

In disordered Weyl semimetals, mechanisms of topological origin lead to the protection against Anderson localization, and at the same time to different types of transverse electromagnetic response—the anomalous Hall and the chiral magnetic effect. We here apply field theory methods to discuss the manifestation of these phenomena at length scales that are beyond the scope of diagrammatic perturbation theory. Specifically, we show how an interplay of symmetry breaking and the chiral anomaly leads to a field theory containing two types of topological terms. Generating the unconventional response coefficients of the system, these terms remain largely unaffected by disorder, i.e., information on the chirality of the system remains visible even at large length scales.

The microscopic stress field provides a unique connection between atomistic simulations and mechanics at the nanoscale. However, its definition remains ambiguous. Rather than a mere theoretical preoccupation, we show that this fact acutely manifests itself in local stress calculations of defective graphene, lipid bilayers, and fibrous proteins. We find that popular definitions of the microscopic stress violate the continuum statements of mechanical equilibrium, and we propose an unambiguous and physically sound definition.

We investigate the trade-off between information gain and disturbance for von Neumann measurements on spin-$\frac{1}{2}$ particles, and derive the measurement pointer state that saturates this trade-off, which turns out to be highly unusual. We apply this result to the question of whether the nonlocality of a single particle from an entangled pair can be shared among multiple observers that act sequentially and independently of each other, and show that an arbitrarily long sequence of such observers can all violate the Clauser-Horne-Shimony-Holt–Bell inequality.

We elaborate an ab initio approach for the evaluation of the one-loop quantum electrodynamical corrections to energy levels of diatomic quasimolecules. The approach accounts for the interaction between an electron and two nuclei in all orders in $Z\alpha$ and can be applied for a wide range of internuclear distances, up to $R\approx 1000\mathrm{fm}$. Based on the developed theory, detailed calculations are performed for the self-energy and vacuum-polarization corrections to the energy of the $1{\sigma }_g$ ground state of the ${\mathrm{U}}^{92+}–{\mathrm{U}}^{91+}$ dimer that can be produced in slow ion-ion collisions. The calculations predict the remarkable energy shift that arises due to the nonspherical contributions to the electron-nuclei potential taken beyond the standard monopole approximation.

Using x-ray scattering, spectroscopy, and density-functional theory, we determine the structure of the oxidation front when a ${\mathrm{UO}}_2$ (111) surface is exposed to oxygen at ambient conditions. In contrast to classical diffusion and previously reported bulk ${\mathrm{UO}}_{2+x}$ structures, we find oxygen interstitials order into a nanoscale superlattice with three-layer periodicity and uranium in three oxidation states: IV, V, and VI. This oscillatory diffusion profile is driven by the nature of the electron transfer process, and has implications for understanding the initial stages of oxidative corrosion in materials at the atomistic level.

${\mathrm{CeRhIn}}_5$ is an itinerant magnet where the ${\mathrm{Ce}}^{3+}$ spins order in a simple helical phase. We investigate the spin excitations and observe sharp spin waves parameterized by a nearest-neighbor exchange, $J_{\mathrm{RKKY}}=0.88\pm 0.05\mathrm{meV}$. At higher energies, the spin fluctuations are heavily damped, where single-quasiparticle excitations are replaced by a momentum- and energy-broadened continuum constrained by kinematics of energy and momentum conservation. The delicate energy balance between localized and itinerant characters results in the breakdown of the single-quasiparticle picture in ${\mathrm{CeRhIn}}_5$.

Magnetic control of the crystal chirality was announced by Saito et al. [Phys. Rev. Lett. 101, (2008)] on the ground of experiments in $\mathrm{Cu}{\mathrm{B}}_2{\mathrm{O}}_4$. This claim has raised a sharp dispute in the literature because it seemed to contradict the fundamental symmetry principles. We settle this dispute on the basis of a high-resolution optical spectroscopy study of excitonic transitions in $\mathrm{Cu}{\mathrm{B}}_2{\mathrm{O}}_4$. We find that a large sublattice-sensitive antiferromagnetic linear dichroism (LD) emerges at the Néel temperature $T_N=21\mathrm{K}$ and show how it could simulate a “magnetic-field control of the crystal chirality.” We prove that the discovered LD is related microscopically to the magnetic Davydov splitting. This LD is highly sensitive to subtle changes in the spin subsystems, which allowed us to observe a splitting of the phase transition into an incommensurate magnetic phase into two transitions ($T_1^{*}=8.5$ and $T_2^{*}=7.9\mathrm{K}$) and to suggest elliptical spiral structures below $T_1^{*}$, instead of a simple circular helix proposed earlier.

We provide a microscopic theory for semiconductor quantum dots that explains the pronounced deviations from the prevalent point-dipole description that were recently observed in spectroscopic experiments on quantum dots in photonic nanostructures. The deviations originate from structural inhomogeneities generating a large circular quantum current density that flows inside the quantum dot over mesoscopic length scales. The model is supported by the experimental data, where a strong variation of the multipolar moments across the emission spectrum of quantum dots is observed. Our work enriches the physical understanding of quantum dots and is of significance for the fields of nanophotonics, quantum photonics, and quantum-information science, where quantum dots are actively employed.

We propose a self-similar kinetic theory of thermal conductivity in a magnetized plasma, and discuss its application to the solar wind. We study a collisional kinetic equation in a spatially expanding magnetic flux tube, assuming that the magnetic field strength, the plasma density, and the plasma temperature decline as power laws of distance along the tube. We demonstrate that the electron kinetic equation has a family of scale-invariant solutions for a particular relation among the magnetic-, density-, and temperature-scaling exponents. These solutions describe the heat flux as a function of the temperature Knudsen number $\gamma$, which we require to be constant along the flux tube. We observe that self-similarity may be realized in the solar wind; for the Helios data $0.3–1\mathrm{AU}$ we find that the scaling exponents for density, temperature, and heat flux are close to those dictated by scale invariance. We find steady-state solutions of the self-similar kinetic equation numerically, and show that these solutions accurately reproduce the electron strahl population seen in the solar wind, as well as the measured heat flux.

Bad-metal (BM) behavior featuring linear temperature dependence of the resistivity extending to well above the Mott-Ioffe-Regel (MIR) limit is often viewed as one of the key unresolved signatures of strong correlation. Here we associate the BM behavior with the Mott quantum criticality by examining a fully frustrated Hubbard model where all long-range magnetic orders are suppressed, and the Mott problem can be rigorously solved through dynamical mean-field theory. We show that for the doped Mott insulator regime, the coexistence dome and the associated first-order Mott metal-insulator transition are confined to extremely low temperatures, while clear signatures of Mott quantum criticality emerge across much of the phase diagram. Remarkable scaling behavior is identified for the entire family of resistivity curves, with a quantum critical region covering the entire BM regime, providing not only insight, but also quantitative understanding around the MIR limit, in agreement with the available experiments.

The two-dimensional Affleck-Kennedy-Lieb-Tasaki (AKLT) model on a honeycomb lattice has been shown to be a universal resource for quantum computation. In this valence bond solid, however, the spin interactions involve higher powers of the Heisenberg coupling $({\overrightarrow{S}}_i·{\overrightarrow{S}}_j{)}^n$, making these states seemingly unrealistic on bipartite lattices, where one expects a simple antiferromagnetic order. We show that those interactions can be generated by orbital physics in multiorbital Mott insulators. We focus on $t_{2g}$ electrons on the honeycomb lattice and propose a physical realization of the spin-$3/2$ AKLT state. We find a phase transition from the AKLT to the Néel state on increasing Hund’s rule coupling, which is confirmed by density matrix renormalization group simulations. An experimental signature of the AKLT state consists of protected, free $S=1/2$ spins on lattice vacancies, which may be detected in the spin susceptibility.

We investigate magnetic order in a lattice of classical spins coupled to an isotropic gas of one-dimensional conduction electrons via local exchange interactions. The frequently discussed Ruderman-Kittel-Kasuya-Yosida effective exchange model for this system predicts that spiral order is always preferred. Here we consider the problem nonperturbatively, and find that such order vanishes above a critical value of the exchange coupling that depends strongly on the lattice spacing. The critical coupling tends to zero as the lattice spacing becomes commensurate with the Fermi wave vector, signaling the breakdown of the perturbative Ruderman-Kittel-Kasuya-Yosida picture, and spiral order, even at weak coupling. We provide the exact phase diagram for arbitrary exchange coupling and lattice spacing, and discuss its stability. Our results shed new light on the problem of utilizing a spiral spin-lattice state to drive a one-dimensional superconductor into a topological phase.

The channeling of spin waves with domain walls in ultrathin ferromagnetic films is demonstrated theoretically and through micromagnetics simulations. It is shown that propagating excitations localized to the wall, which appear in the frequency gap of bulk spin wave modes, can be guided in curved geometries and propagate in close proximity to other channels. For Néel-type walls arising from a Dzyaloshinskii-Moriya interaction, the channeling is strongly nonreciprocal and group velocities can exceed $1\mathrm{km}/\mathrm{s}$ in the long wavelength limit for certain propagation directions. The channeled modes represent an unusual analogy of whispering gallery waves that are one dimensional and nonreciprocal with this interaction. Moreover, a sufficiently strong Dzyaloshinskii-Moriya interaction can create a degeneracy of channeled and propagating modes at a critical wave vector.

It is a salient experimental fact that a large fraction of candidate spin liquid materials freeze as the temperature is lowered. The question naturally arises whether such freezing is intrinsic to the spin liquid (“disorder-free glassiness”) or extrinsic, in the sense that a topological phase simply coexists with standard freezing of impurities. Here, we demonstrate a surprising third alternative, namely, that freezing and topological liquidity are inseparably linked. The topological phase reacts to the introduction of disorder by generating degrees of freedom of a new type (along with interactions between them), which in turn undergo a freezing transition while the topological phase supporting them remains intact.