Physics

Electrical switching of antiferromagnets (AFM) is critical for AFM spintronics. However, electrical pulse-induced N\'eel vector reorientation in AFM insulators, while predicted to occur at much faster timescales than ferromagnetic switching, has only been demonstrated in the quasi-DC regime. Here we report reliable current-induced AFM switching in $\mathrm{Pt}/\ensuremath{\alpha}\text{-F}{\mathrm{e}}_{2}{\mathrm{O}}_{3}$ bilayers using electrical pulses with various durations spanning three orders of magnitude down to 0.3 ns. Together with COMSOL simulations of temperature distributions in our samples for various pulse widths, our results suggest that thermally assisted spin-orbit torque likely play an important role for sub-ns pulses. This work demonstrates the viability of electrical switching of AFM spins using sub-ns pulses.

The ferroics combine the single-hysteresis loop of ferroelectrics with the double-hysteresis loop of antiferroelectrics to form multiple hysteresis loops, which could substantially advance energy storage, electrocaloric cooling, and nonvolatile multistate memory technologies. However, the intentional stabilization of intermediate states that bridge the nonvolatility of ferroelectrics and the field-induced phase transition behavior of antiferroelectrics remains a fundamental challenge. Here, we propose a strategy for preparing lead zirconate (PbZrO 3 ) thin film at low temperature, introducing a stable ferrielectric phase within the antiferroelectric to achieve triple-hysteresis loop under large electric fields. Microstructural features reveal that this behavior is attributable to the presence of Pb Zr antisite defects acting as seeds for polar order, which induce the distinctive triple (↑↑↓) dipole modulation period configuration. To demonstrate the application potential, we evaluated the electrocaloric effect of triple-hysteresis PbZrO 3 thin film based on Maxwell’s relations, the predicted temperature change Δ T can reach −23.76 kelvins, which is ~600% enhancement compared to double-hysteresis PbZrO 3 antiferroelectric thin films. These findings establish a design paradigm for embedding stable ferroelectric switching within antiferroelectrics, which may unlock opportunities for developing high-density energy storage, nonvolatile multistate memory, and highly efficient switching devices.

Borophene, a two-dimensional (2D) boron sheet, has recently gained considerable attention as a postgraphene material owing to its unique properties, such as intrinsic metallic character, lightest element monolayer structure, and high-frequency phonons. These features, together with its theoretically predicted high density of states, make borophene an excellent platform for investigating various quantum phenomena. However, the realization of emergent phenomena is hindered by fabrication challenges and inherently weak electronic correlations within the s and p electron system. Here, we demonstrate a strongly correlated 2D electronic state derived from a honeycomb boron lattice exposed at the surface of ternary boride LaRh 3 B 2 . Using angle-resolved photoemission spectroscopy, we uncover the extended saddle-point van Hove singularity near the Fermi level, which is linked to the substantial lattice expansion and many-body interaction. Moreover, scanning tunneling microscopy reveals the electronic nematicity, which likely originates from the saddle-point instability. Our findings open a pathway to exploring the exotic correlated phenomena in boron-based 2D systems.

Reconfigurable electronics expands device functionality and promises previously unknown computing paradigms, as the channel layer characteristics can be dynamically controlled. Two-dimensional semiconductors coupled with photo-responsive chromic molecules offer a compelling route as atomically thin channels are highly sensitive to molecular conformation changes. However, most demonstrations have been limited to microscale single-flake devices, limiting scalability and technological relevance. Here, we report an optically reconfigurable platform integrating centimeter-scale monolayer WS 2 and WSe 2 with an azobenzene (Azo) overlayer. Wavelength-selective trans-cis Azo photoisomerization generates a reversible interfacial dipole that serves as an optical gate, enabling precise and uniform modulation of both electron and hole densities (~2.5 × 10 12 cm −2 ) over large areas. This optical actuation further supports spatially programmable patterning of optoelectronic properties and delivers repeatable modulation across large transistor arrays. Together, these results establish a scalable smart materials platform for reconfigurable optoelectronics that is light-programmable.

Many conclusions about energy conversion in next-generation photovoltaic devices are gleaned indirectly from optical measurements of exciton dynamics, not directly from photocurrent itself. This method is problematic because optical measurements report on all excitons, not just productive ones. Using a new ultrafast photocurrent spectrometer, we compare exciton dynamics of semiconducting carbon nanotubes measured in films to those measured in devices using photoabsorption- and photocurrent-detected transient and two-dimensional spectroscopies. We find that photoabsorption detection greatly overestimates the importance of long-lived excitons for photovoltaic device performance. Excitons diffuse across nanotubes for picoseconds, but we find that the photocurrent is mostly created by excitons that diffuse little before dissociating at the electron transfer interface within 30 femtoseconds of being created. Thus, scientific conclusions reached from optical-only studies bear little importance to the performance of these devices, calling into question the processes thought critical for efficient photoconversion. This study points to the necessity for directly measuring photocurrent-generating exciton dynamics, not surmising them from optical spectroscopy alone.

Stellar feedback, as a key process regulating the baryon cycle, is thought to greatly redistribute baryonic material inside and outside the dark matter halos (DMHs); however, the observational evidences are lacking. Through stacking analyses of ∼400,000 galaxy spectra from Dark Energy Spectroscopic Instrument (DESI), we find star formation-driven cool outflows in the Mg ii absorption line. Assuming only gravity acts on the launched gas, our calculations reveal that outflows from low-mass galaxies ([Formula: see text]) are capable of escaping beyond the DMHs, which aligns well with our finding in the circumgalactic medium (CGM) absorption along the minor axes of galaxies using background quasars. This research offers indirect evidence that stellar feedback drives the low baryon retention rate in low-mass halos, implicating that baryonic processes within galaxies are connected with the diffuse matter beyond the DMHs.

Porous Carbon Electrodes Ion transport through hierarchical porous carbon electrodes is visualized as multicolored exchange pathways across interconnected micro- and mesopores. The artwork represents 2D EXSY NMR analysis of asymmetric multi-site ion exchange, where distinct kinetic populations reveal fast near-surface motion, slower in-pore diffusion, and direction-dependent mobility at pore-network junctions, linking carbon architecture to electrochemical transport efficiency. More in article number e71010, Henry R. N. B. Enninful and co-workers.

ABSTRACT All‐perovskite tandem solar cells leverage the solid‐solution nature of metal halide perovskites to tune the band gaps of wide‐ and narrow‐bandgap subcells for current matching and high photovoltage. Sn–Pb mixed perovskites with band gaps of approximately 1.2–1.3 eV are attractive bottom absorbers, but Sn‐rich surface regions, depth‐dependent compositional inhomogeneity, and associated band‐alignment issues limit both photocurrent and photovoltage. Here, we introduce a layered‐perovskite‐assisted dry‐contact trimming (LDT) strategy to reconfigure Sn–Pb narrow‐bandgap perovskites after film formation. A Dion–Jacobson‐phase ethylenediammonium lead iodide (EDAPbI 4 ) film is brought into transient solid‐state contact with the Sn–Pb perovskite and then removed after contact annealing. EDAPbI 4 functions as a temporary solid‐state contact partner that removes Sn‐rich surface species and reduces depth‐dependent lattice and compositional inhomogeneity without forming a retained 2D capping layer. This reconfiguration alleviates reverse band bending at the Sn–Pb perovskite/transport‐layer interface, suppresses nonradiative interfacial recombination, and reduces open‐circuit‐voltage losses. The improved lattice/compositional uniformity also enables thick Sn–Pb absorbers to maintain efficient charge collection and high short‐circuit current density. Consequently, single‐junction Sn–Pb devices exceed 24% efficiency, and monolithic all‐perovskite tandem devices surpass 30% with reproducible performance and operational stability. These results identify LDT as a complementary post‐crystallization strategy for engineering mixed perovskite solid‐solutions and their interfaces.

ABSTRACT This Perspective establishes a design filter to guide the rational design of interlayers in anode‐free batteries. Roughness‐dependent closure models are combined with active‐metal inventory accounting during alloying and conversion, including incomplete recovery during cycling. The analysis shows that interlayer feasibility is governed by a narrow intersection of morphology, chemistry, and deposition physics: coatings must be continuous on practical battery substrates while remaining compatible with the finite cathode‐derived metal inventory. Low‐uptake alloy‐forming interlayers can remain inventory‐efficient at moderate thicknesses, whereas conversion oxides and nitrides generally require ultrathin designs unless partial transformation or high recovery efficiency is demonstrated. Deposition route selection is equally critical: line‐of‐sight PVD offers broad materials flexibility but may require inventory‐expensive closure thicknesses on rough substrates, whereas ALD‐type growth can enable conformal coverage at much lower nominal thickness. The resulting design maps provide a unified basis for selecting interlayer chemistry, thickness, substrate roughness, cathode loading, and deposition route under a finite cyclable‐metal inventory.