Incoherence-to-coherence crossover observed in charge-density-wave material 1T-TiSe.

Analogous to the condensation of Cooper pairs in superconductors, the Bose-Einstein condensation (BEC) of electron-hole pairs in semiconductors and semimetals leads to an emergence of an exotic ground state - the excitonic insulator state. In this paper, we study the electronic structure of 1T-TiSe utilizing angle-resolved photoemission spectroscopy and alkali-metal deposition. Alkali-metal adatoms are deposited in-situ on the sample surface, doping the system with electrons.

Coherent optical spin Hall transport for polaritonics at room temperature.

Spin or valley degrees of freedom hold promise for next-generation spintronics. Nonetheless, the macroscopic coherent spin current formations are still hindered by rapid dephasing due to electron scattering, specifically at room temperature. Exciton polaritons offer excellent platforms for spin-optronic devices via the optical spin Hall effect.

Molecular Pairing in Twisted Bilayer Graphene Superconductivity.

We propose a theory for how the weak phonon-mediated interaction (J_{A}=1-4  meV) wins over the prohibitive Coulomb repulsion (U=30-60  meV) and leads to a superconductor in magic-angle twisted bilayer graphene (MATBG). We find the pairing mechanism akin to that in the A_{3}C_{60} family of molecular superconductors: Each AA stacking region of MATBG resembles a C_{60} molecule, in that optical phonons can dynamically lift the degeneracy of the moiré orbitals, in analogy to the dynamical Jahn-Teller effect. Such induced J_{A} has the form of an intervalley anti-Hund's coupling and is less suppressed than U by the Kondo screening near a Mott insulator.

Nucleon Electric Polarizabilities and Nucleon-Pion Scattering at the Physical Pion Mass.

We present a lattice QCD calculation of the nucleon electric polarizabilities at the physical pion mass. Our findings reveal the substantial contributions of the Nπ states to these polarizabilities. Without considering these contributions, the lattice results fall significantly below the experimental values, consistent with previous lattice studies.

Coherent growth of high-Miller-index facets enhances perovskite solar cells.

Obtaining micron-thick perovskite films of high quality is key to realizing efficient and stable positive (p)-intrinsic (i)-negative (n) perovskite solar cells, but it remains a challenge. Here we report an effective method for producing high-quality, micron-thick formamidinium-based perovskite films by forming coherent grain boundaries, in which high-Miller-index-oriented grains grow on the low-Miller-index-oriented grains in a stabilized atmosphere. The resulting micron-thick perovskite films, with enhanced grain boundaries and grains, showed stable material properties and outstanding optoelectronic performances.

Emergent Berezinskii-Kosterlitz-Thouless and Kugel-Khomskii Physics in the Triangular Lattice Bilayer Colbaltate.

Motivated by the experiments on the triangular lattice bilayer colbaltate K_{2}Co_{2}(SeO_{3})_{3}, we consider an extended XXZ model to explore the underlying physics. The model is composed of interacting Co^{2+} dimers on the triangular lattice, where the Co^{2+} ion provides an effective spin-1/2 local moment via the spin-orbit coupling and the crystal field effect. The intradimer interaction is dominant and would simply favor the local spin singlet, and the interdimer interactions compete with the interdimer interaction, leading to rich behaviors.

Observation of Circular Dichroism Induced by Electronic Chirality.

Chiral phases of matter, characterized by a definite handedness, abound in nature, ranging from the crystal structure of quartz to spiraling spin states in helical magnets. In 1T-TiSe_{2} a source of chirality has been proposed that stands apart from these classical examples as it arises from combined electronic charge and quantum orbital fluctuations. This may allow its chirality to be accessed and manipulated without imposing either structural or magnetic handedness.

Cascade Enhancement and Efficient Collection of Single Photon Emission under Topological Protection.

High emission rate, high collection efficiency, and immunity to defects are the requirements of implementing on-chip single photon sources. Here, we theoretically demonstrate that both cascade enhancement and high collection efficiency of emitted photons from a single emitter can be achieved simultaneously in a topological photonic crystal containing a resonant dielectric nanodisk. The nanodisk excited by a magnetic emitter can be regarded as a large equivalent magnetic dipole.

Bidirectional Peptide Translocation through Ultrasmall Solid-State Nanopores.

It is important to obtain the configuration of polypeptides and the sequence information on amino acids for understanding various life processes and many biological applications. Nanopores, as a newly developed single-molecule detection technology, exhibit unique advantages in real-time dynamics detection. Here, we designed a special peptide chain with 10 arginine in the head and achieved successful single-molecule detection by ultrasmall solid-state nanopores (2-3 nm).

Exact work distribution and Jarzynski's equality of a relativistic particle in an expanding piston.

We study the nonequilibrium work in a pedagogical model of relativistic ideal gas. We obtain the exact work distribution and verify Jarzynski's equality. In the nonrelativistic limit, our results recover the nonrelativistic results of Lua and Grosberg [J.

Spin-Enhanced Self-Powered Light Helicity Detecting Based on Vertical WSe-CrI Heterojunction.

Two-dimensional (2D) magnetic semiconductors offer an intriguing platform for investigating magneto-optoelectronic properties and hold immense potential in developing prospective devices when they are combined with valley electronic materials like 2D transition-metal dichalcogenides. Herein, we report various magneto-optoelectronic response features of the vertical hBN-FLG-CrI-WSe-FLG-hBN van der Waals heterostructure. Through a sensible layout and exquisite manipulation, an hBN-FLG-CrI-FLG-hBN heterostructure was also fabricated on identical CrI and FLGs for better comparison.

Suppressed Ion Migration by Heterojunction Layer for Stable Wide-Bandgap Perovskite and Tandem Photovoltaics.

Wide-bandgap (WBG) perovskite has demonstrated great potential in perovskite-based tandem solar cells. The power conversion efficiency (PCE) of such devices has surpassed 34%, signifying a new era for renewable energy development. However, the ion migration reduces the stability and hinders the commercialization, which is yet to be resolved despite many attempts.

Monolayer SnS Schottky barrier field effect transistors: effects of electrodes.

Achieving Ohmic contacts with low resistance is quite desirable for two-dimensional (2D) Schottky barrier field effect transistors (SBFETs). We verify the electrode effect on monolayer (ML) SnS SBFETs using calculations. With the aforeselected ML electrodes from matching lattices and work functions, we obtain n-type Ohmic contacts or quasi-Ohmic contacts to ML SnS with ML 1T-NbTe, ScNF, MoNF, NbCF, and graphene electrodes.

Evolution from a charge-ordered insulator to a high-temperature superconductor in BiSr(Ca,Dy)CuO.

How Cooper pairs form and condense has been the main challenge in the physics of copper-oxide high-temperature superconductors. Great efforts have been made in the 'underdoped' region of the phase diagram, through doping a Mott insulator or cooling a strange metal. However, there is still no consensus on how superconductivity emerges when electron-electron correlations dominate and the Fermi surface is missing.

Electrical Contacts in Monolayer MoSiN Transistors.

The latest synthesized monolayer (ML) MoSiN material exhibits stability in ambient conditions, suitable bandgap, and high mobilities. Its potential as a next-generation transistor channel material has been demonstrated through quantum transport simulations. However, in practical two-dimensional (2D) material transistors, the electrical contacts formed by the channel and the electrode must be optimized, as they are crucial for determining the efficiency of carrier injection.

Utilizing full-spectrum sunlight for ammonia decomposition to hydrogen over GaN nanowires-supported Ru nanoparticles on silicon.

Photo-thermal-coupling ammonia decomposition presents a promising strategy for utilizing the full-spectrum to address the H storage and transportation issues. Herein, we exhibit a photo-thermal-catalytic architecture by assembling gallium nitride nanowires-supported ruthenium nanoparticles on a silicon for extracting hydrogen from ammonia aqueous solution in a batch reactor with only sunlight input. The photoexcited charge carriers make a predomination contribution on H activity with the assistance of the photothermal effect.

Solvent-Engineering-Assisted Ligand Exchange Strategy for High-Efficiency AgBiS Quantum Dot Solar Cells.

As the initial synthesized colloidal quantum dots (CQDs) are generally capped with insulating ligands, ligand exchange strategies are essential in the fabrication of CQD films for solar cells, which can regulate the surface chemical states of CQDs to make them more suitable for thin-film optoelectronic devices. However, uncontrollable surface adsorption of water molecules during the ligand exchange process introduces new defect sites, thereby impairing the resultant device performance, which attracts more efforts devoted to it but remains a puzzle. Here, we develop a solvent-engineering-assisted ligand exchange strategy to revamp the surface adsorption, improve the exchange efficiency, and modulate the surface chemistry for the environmentally friendly lead-free silver bismuth disulfide (AgBiS) CQDs.