Homo-layer flexible BiTe-based films with high thermoelectric performance.

Here, we demonstrate unconventional scalable and sustainable manufacturing of flexible n-type BiTe films via physical vapor deposition and homo-layer fusion engineering. The achieved ultrahigh power factor of up to 30.0 microwatts per centimeter per square kelvin and ultralow lattice thermal conductivity of 0.

Yttrium-Doped Zinc Oxide (ZnYO) Electron Transport Layers: A Pathway to Enhanced Efficiency in PbS Colloidal Quantum Dot Solar Cells.

Significant progress has been achieved in PbS colloidal quantum dot solar cells (CQDSCs) by concentrating on structural engineering, band-alignment engineering, and enhancing the interfacial functionality of colloidal quantum dots (CQDs). Nonetheless, designing a durable and efficient photovoltaic device still represents a considerable obstacle for scientists in this domain. The present work demonstrates that the photovoltaic performance of PbS CQDSCs can be increased by adding 1-5 wt % yttrium into the zinc oxide (YZO) ETL.

Variable π-d orbital hybridization in 2D transition metal-organic frameworks.

Two-dimensional metal-organic frameworks (2D MOFs) have emerged as promising platforms for exploring novel quantum phenomena and tunable electronic functionalities. Here, we investigate π-d orbital hybridization in monolayer M(HAT) (M = Ni, Co, Fe; HAT = 1,4,5,8,9,12-hexaazatriphenylene) frameworks by combining density functional theory (DFT) calculations and scanning tunneling microscopy/spectroscopy (STM/STS) characterization. Despite identical lattice geometries, the Ni-HAT framework exhibits a dispersive, gapless band structure, while the Co- and Fe-HAT frameworks display localized electronic states and semiconducting bandgaps.

Charge Transfer-Stabilized SiP Monolayer: An Unexpected Two-Dimensional Honeycomb on Au(111).

Exploring two-dimensional (2D) honeycomb structures beyond naturally layered materials is increasingly attracting interest, yet discoveries remain limited. Traditional methods often prioritize thermodynamic and dynamic stability, overlooking many inherently unstable materials such as those deviating from electron counting rules. Here, we challenge these traditional limitations by using the Si-P system as a case study.

Sliding Ferroelectric Control of Unconventional Magnetism in Stacked Bilayers.

The control of unconventional magnetism, which displays ferromagnetismlike properties with compensated magnetization, has drawn intense attention for advancing antiferromagnetic spintronics. Here, through symmetry analysis, we propose a general stacking rule, characterized by a connection operator linking two stacked bilayers, for controlling unconventional magnetism via sliding ferroelectricity. Such a rule enables the simultaneous switching of both electric polarization and nonrelativistic spin splitting or anomalous Hall effect in altermagnets, a class of collinear unconventional magnets.

Electrical Switching of Altermagnetism.

Switching magnetism using only electricity is of great significance for industrial applications but remains challenging. We find that altermagnetism, as a newly discovered unconventional magnetism, may open an avenue along this effort. Specifically, to have deterministic switching, i.

Observation of Brownian Motion of a Bose-Einstein Condensate.

We report on the experimental observation of classical Brownian motion in momentum space by a Bose-Einstein condensate (BEC) of rubidium atoms prepared in a hexagonal optical lattice. Upon suddenly increasing the effective atomic mass, the BEC as a whole behaves as a classical rigid body with its center of mass receiving random momentum kicks by a Langevin force arising from atom loss and interactions with the surrounding thermal cloud. Physically, this amounts to selective heating of the BEC center-of-mass degree of freedom by a sudden quench, while with regard to the relative coordinates, the BEC is stabilized by repulsive atomic interactions, and its internal dynamics is suppressed by forced evaporative cooling induced by atom loss.

A General and Interpretable Adatom Model for Classifying Surface Morphologies of Nonmetallic Elements on Metal Substrates.

We present a general and interpretable adatom model that enables the prediction and understanding of stable surface morphologies of nonmetallic elements deposited on metal substrates. By calculating the formation energies of isolated adatoms on various metal surfaces, we reveal the competition between interfacial interactions and the self-aggregation tendencies of the deposited elements. Based on this model, we classify four distinct surface morphologies that arise from nonmetal-metal substrate combinations.

Magnetic geometry induced quantum geometry and nonlinear transports.

The combination of quantum geometry and magnetic geometry in magnets excites diverse phenomena, some critical for antiferromagnetic spintronics. However, very few material platforms have been predicted and experimentally verified to date, with the material pool restricted by the assumed need for strong spin-orbit coupling (SOC). Here, we bypass the need for SOC by considering magnetic order induced quantum geometry and corresponding nonlinear transports (NLTs) in antiferromagnets (AFMs).

Extended Strange Metal Phase in Electron-Doped LaCeCuO.

Landau's Fermi liquid theory offers a profound understanding of conduction electrons in metals. However, many strongly correlated materials, including heavy-fermions, cuprates, iron-based superconductors, and nickelates, exhibit non-Fermi liquid (NFL) behavior. A hallmark is the strange metal state, characterized by linear-in-temperature resistivity and a linear-in-energy single-particle decay rate.

Emergence of nodal-knot transitions by disorder.

Under certain symmetries, degenerate points in three-dimensional metals form one-dimensional nodal lines. These nodal lines sometimes exhibit intricate knotted structures and have been studied in various contexts. As one of the most common physical perturbations, disorder effects often trigger novel quantum phase transitions.

A Mixed-Valence and Mixed-Spin Two-Dimensional Ferromagnetic Metal-Organic Coordination Framework.

Spin-mixed systems with distinct magnetic sublattices present rich physical behaviors and hold promise for magnetic memory, thermomagnetic recording, and optoelectronics. However, most experimental studies remain confined to molecular magnetic salts rather than monolayer two-dimensional (2D) systems. Here, we report the synthesis and characterization of a 2D metal-organic framework (MOF) of Fe(Fe-DPyP), constructed from 5,15-di(4-pyridyl)-10,20-diphenylporphyrin (DPyP) molecules and iron atoms on a Au(111) substrate.

Coulomb Drag in Altermagnets.

An altermagnet is a newly discovered antiferromagnet, characterized by unique anisotropic spin-split energy bands. It has attracted tremendous interest because of its promising potential in information storage and processing. However, measuring the distinctive spin-split energy bands arising from altermagnetism remains a challenge.

A Ternary Reconstruction on the SrTiO(001) Surface.

We revisit the well-studied 2 × 1 SrTiO(001) surface, long presumed to adopt a double-layer TiO reconstruction, and propose a fundamentally new structural model. By combining evolutionary algorithms for global optimization, density-functional theory calculations, and experimental insights, we uncover a ternary surface reconstruction that exhibits substantially lower surface energy under typical experimental conditions compared to previously proposed models. This newly identified structure aligns closely with high-resolution electron microscopy (HREM) observations and explains the experimentally observed Sr precipitation on the surface.

Gigantic-oxidative atomic-layer-by-layer epitaxy for artificially designed complex oxides.

In designing material functionalities for transition metal oxides, lattice structure and -orbital occupancy are key determinants. However, the modulation of these two factors is inherently limited by the need to balance thermodynamic stability, growth kinetics and stoichiometry precision, particularly for metastable phases. We introduce a methodology, namely gigantic-oxidative atomic-layer-by-layer epitaxy (GOALL-Epitaxy), to enhance oxidation power by three to four orders of magnitude beyond conventional pulsed laser deposition and oxide molecular beam epitaxy, while ensuring atomic-layer-by-layer growth of the designed complex structures.

Observation and manipulation of two-dimensional topological polar texture confined in moiré interface.

Topological polar structures in ferroelectric thin films have become an emerging research field for exotic phenomena. Due to the prerequisite of the intricate balance among the intrinsic dipolar anisotropy, the imposed electric and mechanical boundary, the topological polar domains are predominantly formed within complex oxides. Here, combining the microscopic polarization measurement via Piezoresponse Force Microscopy and the atomic displacement mapping via Scanning Transmission Electron Microscopy, we report the direct observation of atomically thin topological polar textures in twisted boron nitride system, which is well confined at the twisted interface.

Ferroelectric Switchable Altermagnetism.

We propose a novel ferroelectric switchable altermagnetism effect: the reversal of ferroelectric polarization is coupled to the switching of altermagnetic spin splitting. We demonstrate the design principles for the ferroelectric altermagnets and the additional symmetry constraints necessary for switching the spin splitting through flipping the electric polarization based on the state-of-the-art spin-group symmetry techniques. We find 22 ferroelectric altermagnets by screening through the 2001 experimental reported magnetic structures in the MAGNDATA database and identify two of them as ferroelectric switchable altermagnets.

Plasmon-mediated dual S-scheme charge transfer in CuS/InS/BiS hollow polyhedrons for efficient Photothermal-Assisted photocatalysis.

Step-scheme (S-scheme) semiconductor junction has garnered considerable attention for its potential applications in photocatalytic energy conversion. However, the photocatalytic activity of S-scheme junctions is restricted by inadequate light absorption and low charge separation efficiency. Herein, a plasmon-mediated dual S-scheme junction is constructed by growing InS and BiS nanoparticles on CuS hollow polyhedrons, exhibiting efficient photothermal-assisted photocatalysis.

Unconventional magnons in collinear magnets dictated by spin space groups.

Magnonic systems provide a fertile playground for bosonic topology, for example, Dirac and Weyl magnons, leading to a variety of exotic phenomena such as charge-free topologically protected boundary modes, the magnon thermal Hall effect and the magnon spin Nernst effect. However, their understanding has been hindered by the absence of fundamental symmetry descriptions of magnetic geometries and spin Hamiltonians primarily governed by isotropic Heisenberg interactions. The ensuing magnon dispersions enable gapless magnon band nodes that go beyond the scenario of representation theory of the magnetic space groups, thus referred to as unconventional magnons.

Strong interaction between plasmon and topological surface state in BiSe/CuS nanowires for solar-driven photothermal applications.

Developing high-performance photothermal materials and unraveling the underlying mechanism are essential for photothermal applications. Here, photothermal performance improved by strong interaction between plasmon and topological surface state (TSS) is demonstrated in BiSe/CuS nanowires. This hybrid, which CuS nanosheets were grown on BiSe nanowires, leverages the plasmon resonance and TSS-induced optical property, generating wide and efficient light absorption.

Ambient-pressure superconductivity onset above 40 K in (La,Pr)NiO films.

The discovery of Ruddlesden-Popper (RP) bilayer nickelate superconductors under high pressure has opened a new chapter in high-transition-temperature superconductivity. However, the high-pressure conditions and presence of impurity phases have hindered comprehensive investigations into their superconducting properties and potential applications. Here we report ambient-pressure superconductivity onset above the McMillan limit (40 K) in RP bilayer nickelate epitaxial thin films.

Quantum geometry in condensed matter.

One of the most celebrated accomplishments of modern physics is the description of fundamental principles of nature in the language of geometry. As the motion of celestial bodies is governed by the geometry of spacetime, the motion of electrons in condensed matter can be characterized by the geometry of the Hilbert space of their wave functions. Such quantum geometry, comprising Berry curvature and the quantum metric, can thus exert profound influences on various properties of materials.

Unified transmission electron microscopy with the glovebox integrated system for investigating air-sensitive two-dimensional quantum materials.

Transmission electron microscopy (TEM) is an indispensable tool for elucidating the intrinsic atomic structures of materials and provides deep insights into defect dynamics, phase transitions, and nanoscale structural details. While numerous intriguing physical properties have been revealed in recently discovered two-dimensional (2D) quantum materials, many exhibit significant sensitivity to water and oxygen under ambient conditions. This inherent instability complicates sample preparation for TEM analysis and hinders accurate property measurements.

Gradient polaritonic surface with space-variant switchable light-matter interactions in 2D moiré superlattices.

Polaritons in two-dimensional (2D) materials provide unique opportunities for controlling light at nanoscales. Tailoring these polaritons via gradient polaritonic surfaces with space-variant response can enable versatile light-matter interaction platforms with advanced functionalities. However, experimental progress has been hampered by the optical losses and poor light confinement of conventionally used artificial nanostructures.