When determining the authorship list for your next paper, be generous yet disciplined.

We are pleased to announce that Sarma Kancharla will assume the position of Chief Editor at PRB, effective April 29, 2024.

The electronic excitations in solid molecular hydrogen at room temperature for pressures varying from 5 to 90 GPa are calculated using quantum Monte Carlo methods and many-body perturbation theory. A crossover from a wide-gap insulator to a semiconductor is observed, showing the changing nature of the excitations from localized molecular (left inset figure) to delocalized (right inset figure) excitations. These findings are in agreement with experimental results, demonstrating the capability of accurately predicting band gaps in many-body systems with strong zero point and thermal effects.

Anomalous Nernst effect (ANE)-based thermopiles can be constructed by combining materials with positive and negative ANE coefficients. While most of the magnetic materials show positive ANE, only a limited number of materials exhibit a negative ANE. Furthermore, the majority of the materials showing negative ANE have low Curie temperatures (TC). Here, the authors demonstrate that high-TC quaternary Heusler alloys with large spin polarizations can exhibit both positive and negative ANE coefficients, depending on their chemical compositions, and hence, can be potential candidates for developing efficient room-temperature ANE-based thermopiles.

For a deeper understanding of the outstanding real-time photorefractive medium LiNbO${}_3$:(Bi,Mg) and excitonic processes in general, stoichiometric LiNbO${}_3$ (SLN) crystals are investigated using low-intensity near-ultraviolet (UV) irradiation and infrared-ultraviolet absorption spectroscopy. Absorption bands separated in SLN:Bi and SLN:(Bi,Mg) are assigned to specific Bi defect types and their persistent association with self-trapped excitons (pinned STEs, PSTEs) generated by near-UV irradiation. Processes on widely differing timescales are predicted for one- and two-photon excitations involving different excited states, relevant for further optimization of the system.

Solving the time-dependent quantum many-body Schrquotodinger equation is a challenging task, especially for states at a finite temperature, where the environment affects the dynamics. Most existing approximating methods are designed to represent static thermal density matrices, 1D systems, and/or zero-temperature states. Here, the authors propose a method to study the real-time dynamics of thermal states in two dimensions, based on thermofield dynamics, variational Monte Carlo, and neural-network quantum states.

Manipulating topological states holds significant interest in the field of condensed matter physics. Here, the authors control the topological phase and corresponding quasiparticle dynamics by managing defects, and further reverse these effects through $in$ $situ$ uniaxial stress control in HfTe${}_5$. The findings showcase the potential of employing both defect chemistry and strain engineering as tools to manipulate topological phase transitions and related many-body physics.

Alkali superoxides have spin and orbital degrees of freedom due to an open $p$ shell of the oxygen ion O${}_2^{-}$ with degenerate $\pi$ orbitals. The complex magnetic, orbital, and structural phase transitions observed experimentally in this family of materials are only partly understood. Geometrical frustration is found, based on density functional theory, to be a key for understanding the rich variety in the behavior of these compounds. Solving the Kugel-Khomskii model for CsO${}_2$ in a mean field reveals an orbital ordering transition below which the material becomes a highly frustrated two-dimensional magnet.

Quenched disorder induced by chemical substitution is potentially important in shaping phase diagrams of strongly correlated quantum materials. Chemical substitution results in local strain, and hence conventional theoretical approaches often treat the effects of chemical substitution as random fields. However, this assumption is not fully justified given the long-range nature of strains in solids. Here, the authors explore the disorder effect arising from chemical substitution in TmVO${}_4$, an insulator, which undergoes ferroquadrupolar (nematic) order at low temperatures. They find quantitative evidence that the local strain fields are indeed correlated. This result implies that the effects of chemical substitution in all-electronic nematic materials need to be treated with greater degrees of sophistication than the ‘simple’ random field Ising model.

Much attention has been given to the spin-orbit coupling (SOC) effect on strongly correlated systems. Here, the authors investigate the electronic structure of the surface layer consisting of rotated RuO${}_6$ octahedrons in strongly correlated Sr${}_2$RuO${}_4$. They demonstrate that the octahedral rotation generates small Fermi pockets. Furthermore, it enhances the strong correlation, which increases the effective SOC, causing high orbital mixing. This result reasonably explains why the orbital-selective Mott transition is not realized in perovskite oxides with crystal distortion of octahedral rotation and tilt.

This work taps into the idea of gauging finite subgroups of global symmetries in conventional systems to obtain unconventional phases and phase transitions, greatly expanding the conventional Landau paradigm. Assisted by analytical anomaly computations and numerical density-matrix renormalization group calculations, the authors map the ordinary superfluid-insulator transition of the Bose-Hubbard model to novel phase transitions between exotic topological and/or symmetry-breaking phases. The general framework has potential applications in cold atom experiments and digital quantum simulators.

Using a single set of measurements of an electronic circuit, researchers have characterized the properties of the topologically protected edge states of a quantum Hall system.

Synopsis on:
Selma Franca et al.
Phys. Rev. B 109, L241103 (2024)

The depth-dependent skyrmion twisting angle evolution in the chiral magnet Cu${}_2$OSeO${}_3$ is found to be temperature dependent, which is unexpected from a standard micromagnetic model. Here, the authors experimentally identify that the extra twisting of the topological textures is strongly correlated with the noncollinear electric polarization from the same material, suggesting a new mechanism that can control the magnetic skyrmions.

The authors clarify here the cause behind the discontinuous bandgap behavior in certain isovalent alloys by studying $\alpha$-(Rh,Ga)${}_2$O${}_3$ alloys using first-principles calculations. This challenges the applicability of conventional empirical continuous rules. They demonstrate that this unusual behavior is due to the unconventional evolution of the wavefunction character at the band edges. This work emphasizes the importance of considering specific band-edge wavefunction character differences in endpoint materials for more accurate predictions of semiconductor alloy properties, which will help in designing better materials for electronics and optoelectronics.

As quantum systems evolve in time, their entanglement usually grows quickly, making tensor network methods inefficient. “Imaginary time” evolution is efficient, but extrapolating back to the real axis is ill-conditioned. Here, the authors show that complex time, a mixture of the two, remains efficient while allowing a controlled reconstruction technique. Therefore, one can reach significantly longer times, which they demonstrate by obtaining high-accuracy results for impurity models at low energies.

Infinite-layer nickelates are an emergent family of unconventional superconductors. Previous investigations have mostly focused on thin film samples, due to the complex crystal growth involving topochemical reductions. Here, the authors present the first spectroscopic investigation of bulk crystal infinite-layer nickelate LaNiO${}_2$ using resonant inelastic x-ray scattering. Their findings indicate that spin excitations are ubiquitous in infinite-layer nickelates, while the presence of charge order remains a subject of debate.

Physical Review B is proud to announce the creation of an Early Career Researcher Advisory Board (ECAB). The 18 inaugural members are listed on the PRB Editorial Team page. We thank them for agreeing to serve. They will act as a focus group and provide advice from their perspective on how PRB can best serve the needs of early career researchers and maintain its important role in condensed matter and materials physics going into the future. The new board members are based in 10 different countries. Stephen Nagler, PRB Lead Editor, will chair the board.

PRB Editorial Team page

APS has selected 156 Outstanding Referees for 2024 who have demonstrated exceptional work in the assessment of manuscripts published in the Physical Review journals. A full list of the Outstanding Referees is available online.