We present measurements demonstrating that copper-oxide high-temperature superconductors can exhibit broken time-reversal symmetry in the absence of external magnetic fields. Using ${\mathrm{Tl}}_2{\mathrm{Ba}}_2{\mathrm{CaCu}}_2{\mathrm{O}}_8$ microbridges, we observe a pronounced superconducting diode effect at 100 K under strictly zero-field conditions. This nonreciprocal response remains unchanged in magnetic fields up to $\pm 100$ Oe. Our results are consistent with recent reports of zero-field diode behavior in ${\mathrm{Bi}}_2{\mathrm{Sr}}_2{\mathrm{CaCu}}_2{\mathrm{O}}_{8+\delta }$ and together they indicate that time-reversal symmetry breaking may be an intrinsic property of the cuprate superconducting state. These findings provide an additional experimental constraint on theoretical descriptions of high-temperature superconductivity and motivate further investigations of possible time-reversal-symmetry-breaking phenomena in cuprates.

The enigmatic puzzle of the Verwey transition in magnetite ${\mathrm{Fe}}_3{\mathrm{O}}_4$ has been unresolved for almost a century. We present an ab initio-based model of the polaron transport combining kinetic Monte Carlo and molecular dynamics calculations to directly describe the coupling of polarons with lattice vibrations. Contrary to the Ihle-Lorenz small-polaron model, we find no significant change in the band structure across the Verwey transition, however, trimeron hopping is observed. The proposed model provides dc conductivity in agreement with experimental data across the Verwey transition.

In this work, we introduce a broad class of circuits, or quantum cellular automata, which we call pairwise difference conserving (PDC) circuits. These models are characterized by local gates that preserve the pairwise difference of local operators (e.g., particle number). Such circuits can be defined on arbitrary graphs in arbitrary dimensions for both quantum and classical degrees of freedom. A key consequence of PDC construction is the emergence of an extensive set of loop charges associated with closed walks of even length on the graph. These charges exhibit a one-dimensional character reminiscent of 1-form symmetries and lead to strong Hilbert space fragmentation. As a case study, we analyze a quasi-one-dimensional ladder geometry, where we characterize all dynamically disconnected sectors by the loop-charge symmetries, providing a complete decomposition of the Hilbert space. For the ladder geometry, we observe clear signatures of nonergodic dynamics even within the largest symmetry sector.

Ferroelectric higher-order topological insulators (HOTIs) exhibit versatile physical properties arising from the interplay between ferroelectric polarization and band topology. This work investigates the topological origin of two classes of two-dimensional (2D) ferroelectric HOTIs with out-of-plane or in-plane polarization, revealing their orbital transport behaviors and the distinct mechanism for engineering orbital Hall conductivity (OHC) via polarization control. Our results demonstrate the unique role of polarization in modulating both the higher-order band topology and orbital transport. A strong coupling between in-plane polarization and higher-order topology is identified, establishing in-plane polarization as an intrinsic means to modulate the OHC plateau within the band gap. Using ${\mathrm{Tl}}_2\mathrm{S}$ and SnS as representative models of the two HOTI types, we demonstrate persistent and electrically tunable orbital transport, respectively. Our study advances the understanding of the coupling among ferroelectricity, higher-order topology, and orbital transport, offering alternative avenues for controllable orbitronics.

As key building blocks for nanoelectronics, graphene nanoribbons (GNRs) have attracted considerable interest over the past two decades. Atomically precise GNRs can be synthesized on Au(111) via on-surface reactions of 10, 10′-9, 9′-bianthryl (DBBA) in two sequential steps: (i) debromination and (ii) cyclodehydrogenation. Despite extensive efforts, the catalytic role of the gold substrate and the physical origin of the adatom effect remain debated, largely due to a lack of electronic-structure-level understanding. Here, we present a comprehensive DFT-D3 study of GNRs on the Au(111) surface by evaluating the energy profiles under four different conditions [vacuum, isolated Au atom, Au(111) surface, and Au adatom on Au(111)]. By combining barrier calculations with electronic-structure analyses, we find that the catalytic effect originates from charge transfer from the C–H (or C–Br) σ bond to the Au adatom, which weakens the bond and lowers the barrier. At 470 K, debromination (barrier 0.753 eV) is kinetically favored, leading to surface-stabilized biradical intermediates that readily couple. Upon heating to 670 K, a thermally activated Au adatom originating from the Au(111) surface lowers the energy barrier of dehydrogenation from 2.650 eV (bare surface) to 2.295 eV. Quantitative transition state theory estimates give half-lives consistent with experimental reaction times (microseconds for debromination at 470 K; hours for cyclodehydrogenation at 670 K). Consequently, we propose that the gold adatom plays a crucial catalytic role in the dehydrogenation process during GNR formation on the Au(111) surface.

The interplay between unconventional superconductivity and altermagnetic order has attracted much attention. In particular, whether spin-triplet superconductivity can be achieved by suppressing altermagnetism remains an open issue. We investigate this issue using a minimal single-orbital Hubbard model on a square lattice with a vacancy superstructure, in which both conventional antiferromagnetic and altermagnetic orders can emerge on an equal footing. We illustrate the existence of a metallic normal phase with altermagnetism even at half-filling due to geometric frustration and Coulomb interaction. Suppressing the altermagnetic long-range order using charge doping can lead to both conventional antiferromagnetic and altermagnetic spin fluctuations. Spin-singlet pairing is always favored when conventional antiferromagnetic spin fluctuations dominate. However, when altermagnetic spin fluctuations dominate, spin-triplet pairing will be induced. Implications of our results for possible material candidates are also briefly discussed.

Atomic orbitals generally exhibit crystal field effect and orbital hybridization arising from the anisotropic environment in matter. Artificial atom, quantum dot with discrete energy levels, offers a unique platform for simulating the electronic features of real atoms. Very recently, the orbital hybridization was proposed and realized in artificial atoms, achieving the reorganization of orbitals of different types. However, the crystal field effect in artificial atoms—namely, the reorganization among orbitals of the same type—has so far remained unexplored. Here, we develop the theory of crystal field effect, based on graphene artificial atoms. We find that in monolayer graphene, the pseudo-time-reversal symmetry prohibits the crystal field effect. But such symmetry is broken in Bernal bilayer graphene, allowing the crystal field effect. Specifically, we propose that the elliptical anisotropy leads to reorganization between a pair of $p$ orbitals. Our numerical calculations and analytical derivations demonstrate the corresponding energy splitting and spatial distributions, confirming the crystal field effect. Our study marks a critical step towards designing quantum matter.

The Mpemba effect, a system farther from equilibrium relaxing faster, has been demonstrated for thermodynamic and symmetry-based quantities in classical, open-quantum, and isolated many-body systems. Whether the same phenomenology extends to quantum resources connected to computational complexity remains unexplored. Here, we investigate the relaxation of coherence, imaginarity, fermionic non-Gaussianity, and magic in subsystems of closed quantum systems evolved under random circuits composed of free gates. We find that coherence and imaginarity display the quantum Mpemba effect (QME) for tilted product states, while non-Gaussianity and magic do not. All four resources exhibit the quantum Pontus-Mpemba effect: a resourceful preheating stage accelerates the subsequent free relaxation. A spectral analysis reveals that the QME is controlled by the overlap of the initial state with the slowest decay mode of the effective Liouvillian, and that generic preheating suppresses this overlap. These results demonstrate that Mpemba physics is not restricted to thermodynamic or symmetry observables, but constitutes a general feature of quantum resource dissipation in complexity-relevant settings.

Physical observables of a macrosystem are functions of state variables that uniquely define the macroscopic state. However, the explicit impact of these variables on the behaviors of magnetoresistance (MR) has not been fully explored. Here, angular-dependent MR of textured cobalt (002) films, which possess a uniaxial magnetocrystalline anisotropy (MCA) with the easy axis ($z$ axis) perpendicular to the isotropic film plane ($xy$ plane), is investigated experimentally and theoretically with two vector state variables: magnetization $\mathbf{m}$ and easy axis $\mathbf{n}$ of the MCA. When the current is applied along the $x$ direction, we found that the angular-dependent MR in different measurement planes shows these distinct scattering mechanisms: it is governed solely by scattering related to m—the conventional anisotropic MR (AMR)—in the $xy$ plane, by the electron scattering related to n in the $yz$ plane (crystalline AMR), and by a combination of both in the $xz$ plane. Notably, the crystalline AMR in the $yz$ plane exhibits a form similar to that of the uniaxial MCA energy. Both the twofold and fourfold terms are independent of the film thickness, and the amplitude of the twofold term is proportional to the twofold constant of MCA. Our results provide a framework for understanding and engineering MR by harnessing the MCA constant.

Altermagnetic multiferroics represent an emerging class of materials that exhibit unique symmetry-protected spin splitting in the absence of net magnetization, holding great promise for spintronic applications. However, achieving deterministic and nonvolatile electric control over their spin-splitting properties remains both a fundamental challenge and a technologically pivotal goal. Here, using first-principles calculations on a $\mathrm{MnPS}{\mathrm{e}}_3/\mathrm{TiGe}{\mathrm{S}}_3$ heterostructure, we demonstrate that sliding ferroelectricity acts as a powerful symmetry knob, enabling reversible switching between $d$-wave and $i$-wave altermagnetic states. This interwave transition is driven by interlayer sliding, which breaks the threefold rotational symmetry and leads to pronounced changes in spin-splitting anisotropy, spin transport behavior, and magneto-optical Kerr signals. Furthermore, we uncover a triple coupling mechanism among intrinsic ferroelectric polarization, sliding ferroelectricity, and altermagnetic symmetry, providing enhanced control over the altermagnetic phase landscape. Our work establishes sliding ferroelectricity as a generic and efficient approach for symmetry engineering in altermagnets and paves the way toward electrically reconfigurable altermagnetic devices.

X-ray photon correlation spectroscopy (XPCS) enables direct access to atomic-scale dynamics in disordered materials, revealing both spontaneous and x-ray-induced relaxation processes. Here, we study two compositionally similar alloy glasses near their glass transition temperatures: the phase-change material (PCM) ${\mathrm{Ge}}_{15}{\mathrm{Sb}}_{85}$ and the non-PCM alloy ${\mathrm{Ge}}_{15}{\mathrm{Te}}_{85}$. Both exhibit an x-ray-induced atomic motion, yet with markedly different responses. ${\mathrm{Ge}}_{15}{\mathrm{Sb}}_{85}$ undergoes an immediate transition to an x-ray-induced yielding state, characterized by stationary dynamics governed solely by the absorbed dose. In contrast, ${\mathrm{Ge}}_{15}{\mathrm{Te}}_{85}$ shows a progressive slowing down of the x-ray-induced dynamics, accompanied by a crossover from compressed to stretched exponential decay in the density autocorrelation functions. This behavior is consistent with the emergence of liquidlike collective motion as supported by de Gennes narrowing in the wave-vector dependence of the dynamics at length scales comparable with the first sharp diffraction peak. Unlike ${\mathrm{Ge}}_{15}{\mathrm{Sb}}_{85}$, this alloy does not reach a stationary regime within experimental timescales, implying that the yielding transition occurs only after thousands of seconds with the available dose rate. Its response is also temperature-dependent: at lower temperatures, the dynamics reflects intrinsic stress relaxation processes, whereas at higher temperatures, it becomes dose-controlled. These findings demonstrate that the dynamical response to x-ray excitation is not determined solely by chemical composition or bonding character, but results from the interplay between irradiation effects and internal stress relaxation pathways.

In fully compensated ferrimagnets (FCFs), the coexistence of vanishing net magnetization and spin polarization provides a unique platform for spintronics. However, their realization remains hindered by the stringent sublattice constraints and electron-counting requirements. Here, we propose a design strategy for FCFs in disordered, off-stoichiometry Heusler-like compounds, using ${\mathrm{TiCo}}_x{\mathrm{Cu}}_y\mathrm{Sn}$ ($1<x+y<2$) as a prototype. We show that the vanishing magnetization is rooted in local orbital-driven exchange between partially occupied Co-$3d$ $e$ orbitals ($d_{x^2-y^2},d_{z^2}$) in inequivalent Co environments, while ${\mathrm{Cu}}^{+}$ provides the charge-compensation degree of freedom. This mechanism manifests as short-range, self-compensated magnetic clusters associated with off-stoichiometric Co/Cu/vacancy configurations within an ordered cubic framework, enabling a zero-net-moment state across a broad, continuously tunable compositional window. Experimental measurements support a compensated ferrimagnetic state with vanishing macroscopic magnetization, together with a low-temperature logarithmic magnetic-scattering contribution that is progressively suppressed by magnetic field. Our findings demonstrate that local orbital-driven clusters enable fully compensated ferrimagnetism beyond the rigid integer-valence-electron-count Slater-Pauling constraint, providing a powerful pathway for engineering functional FCFs.

We present the mixed-configuration approximation (MCA) based on the auxiliary master equation approach impurity solver to study multiorbital correlated systems under equilibrium and nonequilibrium conditions within dynamical mean-field theory (DMFT). We benchmark the method for bulk and layered ${\mathrm{SrVO}}_3$ in equilibrium and apply it to a prototypical nonequilibrium geometry in which a voltage bias is applied perpendicular to the layer via reservoirs held at different chemical potentials. For bulk ${\mathrm{SrVO}}_3$, MCA reproduces the metallic state at moderate interaction strengths, but it overestimates the weight of the lower band relative to quantum Monte Carlo (QMC) and fork tensor product state (FTPS) solvers. With respect to QMC and FTPS, MCA yields an earlier metal-to-insulator transition as the electron-electron interaction is increased. In layered ${\mathrm{SrVO}}_3$ at equilibrium, MCA partially captures the orbital polarization in favor of the in-plane $xy$ orbital, although not as strong as in the DMFT-converged results obtained with QMC. Finally, under applied bias, we observe a pronounced redistribution of orbital occupations, demonstrating that the method captures bias-driven orbital charge transfer in realistic materials in nonequilibrium conditions.

Magnetic rare earth atoms on pyrochlore lattices can produce exotic magnetic states such as spin ice and quantum spin ice. These states are a result of the frustration in the pyrochlore lattice, as well as crystal field degrees of freedom of rare earth atoms, and their interactions with the lattice. Raman scattering spectroscopy, which possesses high spectral resolution and can easily access broad energy and temperature ranges, is an optimal tool to study these excitations and their interactions. In this work we follow the Raman scattering of zone center phonons and crystal field excitations of ${\mathrm{Nd}}^{3+}$ in ${\mathrm{Nd}}_2{\mathrm{Zr}}_2{\mathrm{O}}_7$ and ${\mathrm{Nd}}_2{\mathrm{Ir}}_2{\mathrm{O}}_7$ in the temperature range where these materials are paramagnetic. A comparison between an insulating ${\mathrm{Nd}}_2{\mathrm{Zr}}_2{\mathrm{O}}_7$ and a semimetallic ${\mathrm{Nd}}_2{\mathrm{Ir}}_2{\mathrm{O}}_7$ allows us to distinguish between scattering of phonons on other phonons, crystal field excitations, and electrons, highlighting interactions between these degrees of freedom.

Magnetoresistive materials have been tremendously important for the development of magnetic memory storage and spintronic devices. Recently, the antiferromagnetic Eu $\text{Eu}{X}_2{Pn}_2$ compounds, with $X$ being a transition metal and $\mathit{Pn}$ being a pnictogen, have seen intensive research interest due to their unusual anomalous Hall effect behavior and pronounced resistive anomaly near the Néel temperature ($T_{\text{N}}$). These magnetotransport phenomena have been interpreted in the context of short-ranged ferromagnetic fluctuations, magnetic polaron formation, canted spin configurations, and temperature-dependent metal-insulator transitions in the electronic structure. Here, we report the observation of such a pronounced resistivity anomaly in ${\mathrm{EuZn}}_2{\mathrm{As}}_2$ near $T_{\text{N}}=19$ K. We demonstrate the suppression of this anomaly using applied magnetic fields, both in plane and out of plane. To further interpret the origin of the observed transport behavior, we studied the temperature-dependent electronic structure using combined angle-resolved photoemission spectroscopy and first-principles density functional theory calculations, which exhibits limited modifications to the bands across $T_{\text{N}}$ away from the Fermi energy. This lack of involvement of the electronic structure indicates a spin-scattering origin of the aforementioned transport properties, rather than a reconstruction of the Fermi surface.

${\mathrm{CeRh}}_2{\mathrm{As}}_2$ has been receiving considerable attention due to its unusual two-phase superconductivity. The superconducting (SC) phase appears at $T_{\mathrm{c}}=0.35$ K in an ordered state (phase I) of the $\mathrm{Ce}\text{−}4f$ moments, which develops below $T_0=0.55$ K. The microscopic nature of phase I has not been fully established yet. We report a single-crystal study of the effect of La substitution on these low-temperature phases in ${\mathrm{Ce}}_{1-\mathit{x}}{\mathrm{La}}_{\mathit{x}}{\mathrm{Rh}}_2{\mathrm{As}}_2$ up to $\mathit{x}=0.1$. The lattice parameters increase monotonically with $x$, corresponding to an effective negative pressure of approximately $-0.3$ GPa for $x=0.1$. While the ${\mathrm{Ce}}^{3+}$ local valence state and the non-Fermi-liquid behavior are preserved, the resistivity coherence maximum $T_{\max }^{*}\approx 45$ K in the pristine sample shifts to lower temperatures with increasing $x$, indicating a suppression of the Kondo energy scale upon lattice expansion. On the other hand, both $T_{\mathrm{c}}$ and $T_0$ are rapidly suppressed to below 0.1 K for $x>0.05$. Notably, such a rapid decrease of $T_{\mathrm{c}}$ under moderate negative pressure is unexpected, but is rather consistent with a substitution-induced disorder effect which leads to strong pair breaking in unconventional superconductors. The observed fragility of phase I under both pressure and disorder may imply its itinerant origin.