We study the escort probability distribution function of work done during an interaction quantum quench of Luttinger liquids. It crosses over from the thermodynamic to the small system limit with increasing $a$, which is the order of the escort distribution, and depends on the universal combination $\left[\right|K_i-K_f{|/(K_i+K_F)]}^a$, with $K_i$, $K_f$ the initial and final Luttinger liquid parameters, respectively. From its characteristic function, the diagonal Rényi entropies and the many-body inverse participation ratio (IPR) are determined to evaluate the information content of the time-evolved wave function in terms of the eigenstates of the final Hamiltonian. The hierarchy of overlaps is dominated by that of the ground states. The IPR exhibits a crossover from Gaussian to power-law decay with increasing interaction quench parameter.

We employ a combination of density functional theory and dynamical mean-field theory to investigate the electronic structure of the recently synthesized insulator ${\mathrm{BaCrO}}_3$. Our calculations show that Hund's coupling is responsible for strong correlation effects, which are however not sufficient to turn the system insulating without breaking any symmetry. The Hund's correlated metal is however unstable with respect to orbital ordering, which indeed makes the system insulating. The orbitally ordered insulator favors Jahn-Teller distortions and a secondary magnetic ordering.

We study the possible ground-state configurations of two strongly coupled chains of charge neutral spin-$\frac{3}{2}$ fermionic atoms interacting via short-range van der Waals interaction. The coupling between the two chains is realized by a relatively large hopping amplitude. Exploiting the fact that such a ladder configuration can be mapped to an effective one-band model, we analyze the emerging ground states of the system. We show that various spatially inhomogeneous states, valence-bond states, and plaquette states compete depending on the filling and the ratio of the interaction strengths in the singlet and quintet scattering channel. We find that a Luttinger liquid state is the ground state of the strongly coupled ladder in an extended region of the parameter space, and we also show that a topologically nontrivial charge Haldane state can emerge in the strongly coupled ladder at quarter and three-quarter fillings.

Recent experiments in the underdoped regime of the hole-doped cuprates have found evidence for an incommensurate charge density-wave state. We present an analysis of the charge ordering instabilities in a metal with antiferromagnetic correlations, where the electronic excitations are coupled to the fractionalized excitations of a quantum fluctuating antiferromagnet on the square lattice. The resulting charge density-wave state emerging out of such a fractionalized Fermi liquid (FL*) has wave vectors of the form $(\pm Q_0,0),(0,\pm Q_0)$, with a predominantly $d$-form factor, in agreement with experiments on a number of different families of the cuprates. In contrast, as previously shown, the charge density-wave instability of a nearly antiferromagnetic metal with a large Fermi surface, interacting via short-range interactions, has wave vectors of the type $(\pm Q_0,\pm Q_0)$. Our results show that the observed charge density-wave appears as a low-energy instability of a fractionalized metallic state linked to the proximity to an antiferromagnetic insulator, and the pseudogap regime can be described by such a metal at least over intermediate length and energy scales.

We here report an investigation of the electronic states in the $R\mathrm{F}{\mathrm{e}}_2{\mathrm{O}}_4(R=\mathrm{Lu},\mathrm{Yb},\mathrm{Tm},\mathrm{Y})$ mixed-valence ferrites by means of soft x-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD) measurements together with ab initio theoretical calculations. The presence of ${\mathrm{Fe}}^{+2}$ and ${\mathrm{Fe}}^{+3}$ pure ionic species is discarded in the XAS spectra at the $\mathrm{O}K$ edge in both experimental data and simulations based on the multiple scattering theory. Similarly, no trace of $\mathrm{F}{\mathrm{e}}^{+2}/\mathrm{F}{\mathrm{e}}^{+3}$ contributions is detected in the XMCD spectra at the $\mathrm{Fe}K$ edge. On the other hand, the XAS and XMCD spectra at the $\mathrm{Fe}{L}_{2,3}$ edges can be well described in terms of $\mathrm{F}{\mathrm{e}}^{+2}/\mathrm{F}{\mathrm{e}}^{+3}$ contributions, and are also supported by multiplet calculations. This finding can be interpreted as the existence of a mixture of $3d^5/3d^6$ configurations at the Fe atoms. Alternative ferrimagnetic spin orderings based on a trimodal Fe valence distribution are also proposed and discussed. Finally, a possible explanation for the strong dependence of the $\mathrm{Fe}{L}_{2,3}$ edges XMCD signal magnitude on both the sample surface preparation and detection method is presented.

We perform density functional theory plus dynamical mean-field theory calculations to investigate internal charge transfer in a superlattice composed of alternating layers of vanadate and manganite perovskite and Ruddlesden-Popper structure materials. We show that the electronegativity difference between vanadium and manganese causes moderate charge transfer from ${\mathrm{VO}}_2$ to ${\mathrm{MnO}}_2$ layers in both perovskite and Ruddlesden-Popper-based superlattices, leading to hole doping of the ${\mathrm{VO}}_2$ layer and electron doping of the ${\mathrm{MnO}}_2$ layer. Comparison of the perovskite and Ruddlesden-Popper-based heterostructures shows that apical oxygen motion in the perovskite superlattice enhances charge transfer. Our first principles simulations demonstrate that the combination of internal charge transfer and quantum confinement provided by heterostructuring is a powerful approach to engineering electronic structure and tailoring correlation effects in transition metal oxides.

The magnetic properties and Mott transition of the half-filled Hubbard model on the $\frac{1}{5}$-depleted square lattice with frustration are studied at zero temperature by the variational cluster approximation. The $(\pi ,\pi )$ Néel ordering is stable in a wide region of the phase diagram and almost completely veils the nonmagnetic Mott transition for the nonfrustrated case. However, $(\pi ,\pi )$ Néel ordering is severely suppressed by the frustration, and even with moderate frustrations the nonmagnetic Mott transition takes place in the range where the intradimer hoppings are larger than the intraplaquette hoppings.

We report coherently controlled photocurrent at room temperature in subpicosecond dynamics. The photocurrent intensity shows a periodic change depending on the time interval between the phase-locked pulses. We identify the carrier generation due to shallow acceptors in bulk GaAs by measuring the photocurrent beat period. The non-instantaneous photocurrent beat expresses the ultrafast coherent dynamics, including the dephasing process of the photogenerated carriers. We also demonstrate photocurrent direction control through manipulation of the localized states.

We theoretically study the interplay of spin-orbit and hyperfine interactions in dynamical nuclear polarization in two-electron semiconductor double quantum dots near the singlet-triplet ($S-T_{+}$) anticrossing. The goal of the scheme under study is to extend the singlet-triplet ($S-T_0$) qubit decoherence time $T_2^{*}$ by dynamically transferring the polarization from the electron spins to the nuclear spins. This polarization transfer is achieved by cycling the electron spins over the $S-T_{+}$ anticrossing. Here, we investigate, both quantitatively and qualitatively, how this hyperfine-mediated dynamical polarization transfer is influenced by the Rashba and Dresselhaus spin-orbit interaction. In addition to $T_2^{*}$, we determine the singlet return probability $P_s$, a quantity that can be measured in experiments. Our results suggest that the spin-orbit interaction establishes a mechanism that can polarize the nuclear spins in the direction opposite to that of hyperfine-mediated nuclear spin polarization. In materials with relatively strong spin-orbit coupling, this interplay of spin-orbit and hyperfine-mediated nuclear spin polarizations prevents any notable increase in the $S-T_0$ qubit decoherence time $T_2^{*}$.

We measure transient spin accumulation in Cu, Ag, and Au by time-resolved magneto-optical Kerr effect. The transient spin current is generated by ultrafast demagnetization of a ferromagnetic [Co/Pt] layer, and spin accumulates in an adjacent normal metal, Cu, Ag, or Au by spin diffusion. The magnitude of the Kerr rotation is described by an off-diagonal conductivity tensor that is proportional to spin accumulation and spin-orbit coupling. From comparisons between observed Kerr rotations and calculated spin accumulations, we determine the strength of spin-orbit coupling of conduction electrons in Cu, Ag, and Au to be 0.02, 0.01, and $0.12\mathrm{eV}$, respectively.

Spin ice materials, such as ${\mathrm{Dy}}_2{\mathrm{Ti}}_2{\mathrm{O}}_7$ and ${\mathrm{Ho}}_2{\mathrm{Ti}}_2{\mathrm{O}}_7$, are highly frustrated magnetic systems. Their low-temperature strongly correlated state can be mapped onto the proton disordered state of common water ice. As a result, spin ices display the same low-temperature residual Pauling entropy as water ice, at least in calorimetric experiments that are equilibrated over moderately long-time scales. It was found in a previous study [X. Ke et al., Phys. Rev. Lett. 99, 137203 (2007)] that, upon dilution of the magnetic rare-earth ions (${\mathrm{Dy}}^{3+}$ and ${\mathrm{Ho}}^{3+}$) by nonmagnetic yttrium (${\mathrm{Y}}^{3+}$) ions, the residual entropy depends nonmonotonically on the concentration of ${\mathrm{Y}}^{3+}$ ions. A quantitative description of the magnetic specific heat of site-diluted spin ice materials can be viewed as a further test aimed at validating the microscopic Hamiltonian description of these systems. In this work, we report results from Monte Carlo simulations of site-diluted microscopic dipolar spin ice models (DSIM) that account quantitatively for the experimental specific-heat measurements, and thus also for the residual entropy, as a function of dilution, for both ${\mathrm{Dy}}_{2-x}{\mathrm{Y}}_x{\mathrm{Ti}}_2{\mathrm{O}}_7$ and ${\mathrm{Ho}}_{2-x}{\mathrm{Y}}_x{\mathrm{Ti}}_2{\mathrm{O}}_7$. The main features of the dilution physics displayed by the magnetic specific-heat data are quantitatively captured by the diluted DSIM up to 85% of the magnetic ions diluted ($x=1.7$). The previously reported departures in the residual entropy between ${\mathrm{Dy}}_{2-x}{\mathrm{Y}}_x{\mathrm{Ti}}_2{\mathrm{O}}_7$ versus ${\mathrm{Ho}}_{2-x}{\mathrm{Y}}_x{\mathrm{Ti}}_2{\mathrm{O}}_7$, as well as with a site-dilution variant of Pauling's approximation, are thus rationalized through the site-diluted DSIM. We find for 90% ($x=1.8$) and 95% ($x=1.9$) of the magnetic ions diluted in ${\mathrm{Dy}}_{2-x}{\mathrm{Y}}_x{\mathrm{Ti}}_2{\mathrm{O}}_7$ a significant discrepancy between the experimental and Monte Carlo specific-heat results. We discuss possible reasons for this disagreement.

We report an electronic structure study on ${\mathrm{LaO}}_{1-x}{\mathrm{F}}_x{\mathrm{BiSe}}_2$ $(x=0.18)$ by means of photoelectron spectromicroscopy. The Fermi surfaces and band dispersions are basically consistent with the band-structure calculations on ${\mathrm{BiS}}_2$-based materials, indicating that the electron correlation effects may be irrelevant to describe physics of the new ${\mathrm{BiSe}}_2$ system. In ${\mathrm{LaO}}_{1-x}{\mathrm{F}}_x{\mathrm{BiSe}}_2$ $(x=0.18)$, the area of the Fermi pockets is estimated to be $0.16\pm 0.02$ per Bi, consistent with the amount of F substitution. Although the spectromicroscopy technique avoids the effect of microscale inhomogeneity for angle-resolved photoemission spectroscopy (ARPES), the ARPES spectral features are rather broad in the momentum space, indicating the likely effect of local disorder in the ${\mathrm{BiSe}}_2$ layer.

Quantized vortices are remarkable manifestations on a macroscopic scale of the coherent nature of quantum fluids, and the study of their properties is of fundamental importance for the understanding of this peculiar state of matter. Cavity polaritons, due to their double light-matter nature, offer a unique controllable environment to investigate these properties. In this paper we theoretically investigate the possibility to deterministically achieve the annihilation of a vortex with an antivortex through an increase of the polariton density in the region surrounding the vortices. Moreover, we demonstrate that by means of this mechanism an array of vortex-antivortex pairs can be completely washed out.

The dynamics following the photoionization of neutral Rb and Cs atoms residing in a dimple at the surface of a superfluid ${}^4\mathrm{He}_{1000}$ nanodroplet has been investigated within time-dependent density functional theory, complementing a previous study on Ba. The calculations reveal that structured high density helium solvation layers form around both the ${\mathrm{Rb}}^{+}$ and ${\mathrm{Cs}}^{+}$ cation on a picosecond time scale, forming so-called snowballs. In contrast to the ${\mathrm{Rb}}^{+}$ ion, ${\mathrm{Cs}}^{+}$ is not solvated by the ${}^4\mathrm{He}_{1000}$ droplet but rather desorbs from it as a ${\mathrm{Cs}}^{+}{\mathrm{He}}_n$ snowball. This outcome is partially related to the large size of ${\mathrm{Cs}}^{+}$ cation in relation to the helium droplet as is revealed by calculations performed using a planar helium surface. The large droplet deformations induced by the solvation of the ${\mathrm{Rb}}^{+}$ cation is found to lead to efficient nucleation of quantized vortex loops or rings.

The edge currents of two-dimensional topological chiral superconductors with nonzero Cooper pair angular momentum—e.g., chiral $p$-, $d$-, and $f$-wave superconductivity—are studied. Bogoliubov–de Gennes and Ginzburg-Landau calculations are used to show that in the continuum limit, only chiral $p$-wave states have a nonzero edge current. Outside this limit, when lattice effects become important, edge currents in non-$p$-wave superconductors are comparatively smaller, but can be nonzero. Using Ginzburg-Landau theory, a simple criterion is derived for when edge currents vanish for non-$p$-wave chiral superconductivity on a lattice. The implications of our results for putative chiral superconductors such as ${\mathrm{Sr}}_2{\mathrm{RuO}}_4$ and ${\mathrm{UPt}}_3$ are discussed.

Kondo-hole substitution is a unique probe for exploring the interplay of interactions, $f$-electron dilution, and disorder in heavy-fermion materials. Within the diluted periodic Anderson model, we investigate the changes in single-particle dynamics as well as response functions, as a function of Kondo-hole concentration ($x$) and temperature. We show that the spectral weight transfers due to Kondo-hole substitution have characteristics that are different from those induced by temperature; the dc resistivity crosses over from a highly nonmonotonic form with a coherence peak in the $x\to 0$ limit to a monotonic single-impurity-like form that saturates at low temperature. The thermopower exhibits a characteristic maximum as a function of temperature, the value of which changes sign with increasing $x$, and its location is shown to correspond to a low energy scale of the system. The Hall coefficient also changes sign with increasing $x$ at zero temperature and is highly temperature dependent for all $x$. As $x$ is increased beyond a certain $x_c$, the Drude peak and the mid-infrared peak in the optical conductivity vanish almost completely; a peak in the optical scattering rate melts and disappears eventually. We discuss the above-mentioned changes in the properties in terms of a crossover from coherent, Kondo lattice behavior to single-impurity-like, incoherent behavior with increasing $x$. A comparison of theory with experiments carried out for the dc resistivity and the thermopower of ${\mathrm{Ce}}_{1-x}{\mathrm{La}}_x{\mathrm{B}}_6$ yields good agreement.

Nitrogen-vacancy centers in diamond (NV) attract great attention because they serve as a tool in many important applications. The NV center has a polarizable spin $S=1$ ground state and its spin state can be addressed by optically detected magnetic resonance (ODMR) techniques. The $m_S=0$ and $m_S=\pm 1$ spin levels of the ground state are separated by about 2.88 GHz in the absence of an external magnetic field or any other perturbations. This zero-field splitting (ZFS) can be probed by ODMR. As this splitting changes as a function of pressure and temperature, the NV center might be employed as a sensor operating at the nanoscale. Therefore, it is of high importance to understand the intricate details of the pressure and temperature dependence of this splitting. Here we present an ab initio theory of the ZFS of the NV center as a function of external pressure and temperature including detailed analysis on the contributions of macroscopic and microscopic effects. We found that the pressure dependence is governed by the change in the distance between spins as a consequence of the global compression and the additional local structural relaxation. The local structural relaxation contributes to the change of ZFS with the same magnitude as the global compression. In the case of temperature dependence of ZFS, we investigated the effect of macroscopic thermal expansion as well as the consequent change of the microscopic equilibrium positions. We could conclude that theses effects are responsible for about 15% of the observed decrease of ZFS.

Graphene is an interesting material for spintronics, showing long spin relaxation lengths even at room temperature. For future spintronic devices it is important to understand the behavior of the spins and the limitations for spin transport in structures where the dimensions are smaller than the spin relaxation length. However, the study of spin injection and transport in graphene nanostructures is highly unexplored. Here we study the spin injection and relaxation in nanostructured graphene with dimensions smaller than the spin relaxation length. For graphene nanoislands, where the edge length to area ratio is much higher than for standard devices, we show that enhanced spin-flip processes at the edges do not seem to play a major role in the spin relaxation. On the other hand, contact induced spin relaxation has a much more dramatic effect for these low dimensional structures. By studying the nonlocal spin transport through a graphene quantum dot we observe that the obtained values for spin relaxation are dominated by the connecting graphene islands and not by the quantum dot itself. Using a simple model we argue that future nonlocal Hanle precession measurements can obtain a more significant value for the spin relaxation time for the quantum dot by using high spin polarization contacts in combination with low tunneling rates.

We show that the resonant interactions between phonons in one dimension may be treated consistently within quantum hydrodynamics by the introduction of phonon dispersion. In this way the physics of a nonlinear Luttinger liquid may be described in terms of hydrodynamic (i.e., bosonized) variables without the introduction of impurities at the outset, and gives a complementary view on the mobile impurity model from the hydrodynamics. We focus on the calculation of the dynamic structure factor for a model with quadratic dispersion, which has the Benjamin-Ono equation of fluid dynamics as its equation of motion. We find singular behavior in the vicinity of upper and lower energetic thresholds corresponding to phonon and soliton branches of the classical theory, which may be benchmarked against known results for the Calogero-Sutherland model.