Epitaxy growth and accurate doping of wafer-scale two-dimensional (2D) semiconductor single crystals are two crucial issues to break the scaling limitation of transistors. Despite remarkable progresses have been realized in preparing large-area 2D n-type semiconductor single crystals, the epitaxy growth of wafer-scale p-type semiconductor single crystals have yet to be realized. Here an in-situ hole doping strategy is proposed to control the domain orientation and modulate the electronic property of monolayer MoS2, which enable the achievement of centimeter-sized p-type semiconductor single crystals. The introduction of hole dopants (e.g., V2O5, NH4VO3, and VCl3) contributes to the parallel steps formation on sapphire surfaces to induce the unidirectional monolayer MoS2 domains nucleation. Meanwhile, the electronic property of monolayer MoS2 is also changed from n-type semiconducting to p-type. Benefiting from the different doping abilities of V2O5, NH4VO3, and VCl3, the V doping concentrations can be regulated within a large range from 0.36 to 12.60 at%, which delivers an excellent hole mobility (17.6 cm2·V−1·s−1). This work provides a new avenue for synthesizing wafer-scale 2D p-type semiconductor single crystals, which will enrich the device functions and extend Moore’s law.
Exchange bias, which typically requires a coupled ferromagnetic and antiferromagnetic interface, plays a key role in enhancing data storage technologies by reducing noise and improving signal readability. In this study, we investigate the exchange bias phenomenon in surface-oxidized van der Waals material Fe3GaTe2, which exhibits a blocking temperature of approximately 280 K — near room temperature. This behavior is particularly significant, as achieving room-temperature exchange bias has been challenging, potentially due to the lack of high-Néel-temperature van der Waals antiferromagnetic materials. Using ab initio calculations and magneto-optical methods, we propose a model to explain the origin of the exchange bias, thereby circumventing the need for complex fabrication typically required in transport measurements. Our findings suggest that surface oxidation plays a crucial role in realizing exchange bias behavior, which is strongly dependent on temperature, interfacial spin-pinning states, and the interplay between ferromagnetic and antiferromagnetic interactions. We also examine the stability and uniformity of this behavior in flakes of various thicknesses. These insights provide valuable understanding of near-room-temperature exchange bias in van der Waals materials, opening up possibilities for their integration into next-generation spintronic and data storage applications.
The stability of matter is a historical problem that tackles the linearity of the bulk energy with the total number of particles M. The classical and quantum variants have been proved using mostly Coulomb interaction between electrons and nuclei, either fixed or submitted to thermal fluctuation. The classical dipole−dipole interaction is addressed here as the sole energy on regular tilings. We prove that the system on any regular (periodic) grid is always stable. The aperiodic or quasicrystal instance is conjectured and numerically illustrated for the particular cases of the Penrose P2 and the recently discovered hat monotiles.
Honeycomb lattice Kitaev magnets exhibit exotic magnetic properties governed by the Kitaev interaction. This study delves into
We investigate the squared sublattice magnetizations and magnetic excitations of a
With the growing demand for miniaturization and low power consumption in optoelectronic devices, self-powered photodetectors (SPPDs) have attracted widespread attention due to their excellent performance without external power. Two-dimensional (2D) layered transition metal dichalcogenides (TMDs) are exemplary materials for heterojunction SPPDs, owing to their distinctive properties such as the absence of surface dangling bonds, high carrier mobility, tunable bandgap, and strong light−matter interaction. Thanks to their high-quality heterojunction interfaces, SPPDs based on TMDs exhibit broad spectral response, high detectivity, and ultrafast response speed. Moreover, various interface modulation strategies have been developed to enhance photoelectric conversion efficiency. In this review, we summarize recent advancements in heterojunction modulation strategies based on TMDs. First, the structural, optical, and electronic properties of TMDs are systematically introduced. Next, the strategies for energy band alignment engineering, interface engineering, growth modulation, and carrier modulation are reviewed according to the vertical-structure and lateral-structure photodetectors. Finally, we summarize the challenges of TMDs-based SPPDs and propose possible future research directions. This review offers a forward-looking perspective on TMDs-based SPPDs.
Broadband absorbers based on resonant acoustic metamaterials often require intricate designs, yet this complexity inherently restricts their bandwidth, robustness, and manufacturability. To overcome these constraints, we present a composite sound-absorbing metamaterial that combines multiple resonance coupling with quality factor modulation, leveraging micro-perforated plates and porous materials. This metamaterial exhibits near-perfect broadband sound absorption across a frequency range spanning from 340 to 3200 Hz. In addition, composite metamaterials exhibit greater robustness compared to resonant metamaterials, demonstrating better noise control capabilities in diffuse sound fields. This work uses a new mechanism to revitalize traditional sound-absorbing materials and bring them back to prominence in noise control. We anticipate that this innovative solution will address noise control challenges in demanding environments and provide a reference for further development of sound-absorbing metamaterials.
The duality of left and right eigenvectors underpins the comprehensive understanding of many physical phenomena. In Hermitian systems, left and right eigenvectors are simply Hermitian-conjugate pairs. In contrast, non-Hermitian eigenstates have left and right eigenvectors that are distinct from each other. However, despite the tremendous interest in non-Hermitian physics in recent years, the roles of non-Hermitian left eigenvectors (LEVs) are still inadequately explored. Their physical consequences and observable effects remain elusive, so much so that LEVs seem largely like objects of primarily mathematical purpose. In this study, we present a method based on the non-Hermitian Green’s function for directly retrieving both LEVs and right eigenvectors (REVs) from experimentally measured steady-state responses. We validate the effectiveness of this approach in two separate acoustic experiments: one characterizes the non-Hermitian Berry phase, and the other measures extended topological modes. Our results not only unambiguously demonstrate observable effects related to non-Hermitian LEVs but also highlight the under-appreciated role of LEVs in non-Hermitian phenomena.
Wireless power transfer (WPT) offers significant advantages, particularly due to its flexibility, enabling diverse applications. However, conventional single-transmitter, single-receiver systems are limited by their sensitivity to lateral disturbances, frequency instability, and strict distance constraints. Recently, multiple-transmitter, single-receiver (MTSR) systems have gained attention for their potential to enhance system flexibility and reliability. In this work, we propose an efficient second-order anti-parity‒time (anti-PT) symmetry by introducing two transmitters that simultaneously exchange energy with the external channel. This concept is further extended to third-order anti-PT symmetry for efficient WPT in MTSR systems. By leveraging interference between shared sources, we construct virtual coupling instead of relying on traditional resistive losses. Remarkably, our system maintains frequency stability, broad bandwidth, and robust high-efficiency power transfer even when the resonant frequencies of the transmitter and receiver coils are mismatched. This innovation challenges conventional understanding and opens new directions for WPT technology.
A central challenge in nuclear physics is understanding quantum many-body systems governed by the strong nuclear force. The inherent complexity of these systems, combined with the limitations of classical computational methods, underscores the need for new approaches to study nuclear structure and dynamics. Here, we demonstrate that a spin-based digital quantum simulator using nuclear magnetic resonance, where nuclear spins simulate interacting fermions, offers a powerful tool to address this challenge. As a first step, we experimentally simulate the Agassi model, which encapsulates the interplay between collective and single-particle behaviors in finite nuclei. By representing nucleons as both bosons (nucleon pairs) and fermions (individual unpaired nucleons), the Agassi model captures highly non-linear interactions and is particularly suited for studying nuclear phase transitions, such as those between spherical and deformed shapes. We experimentally measure the correlation function as an order parameter during the evolution of the many-body system, successfully detecting a quantum phase transition. Specifically, we observe a sharp transition between the symmetric phase and the broken symmetry phase. This work underscores the potential of quantum simulation as a transformative tool in nuclear physics, particularly for exploring complex quantum many-body systems with applications in nuclear structure and reaction dynamics.
Compared with passive interferometers, SU(1,1) interferometers demonstrate superior phase sensitivity due to the incorporation of nonlinear elements that enhance their ability to detect phase shifts. Nevertheless, the measurement precision of these interferometers is considerably impacted by photon losses, particularly internal losses, thereby restricting the overall accuracy of measurements. Addressing these issues is essential to fully realize the advantages of SU(1,1) interferometers in practical applications. Among the available resources in quantum metrology, squeezing stands out as one of the most practical and efficient approaches. We propose a theoretical scheme to improve the precision of phase measurement using homodyne detection by implementing the single-path local squeezing operation (LSO) inside the SU(1,1) interferometer, with the coherent state and the vacuum state as the input states. We not only analyze the effects of the single-path LSO scheme on the phase sensitivity and the quantum Fisher information (QFI) under both ideal and photon-loss cases but also compare the impact of different squeezing parameters r on the system performance. Our findings reveal that the internal single-path LSO scheme can significantly enhance the phase sensitivity and QFI by strengthening intramode correlations while weakening intermode correlations, thereby effectively improving the robustness of the SU(1,1) interferometer against photon losses.
We investigate the quantum many-body dynamics of ultracold atom−molecule conversion using a Floquet spin-boson model, where the periodic energy detuning between molecules and atomic pairs is utilized to explore various dynamical regimes. We find that the upper bound of the adiabatic driving frequency increases continuously with the strength of molecule−molecule interactions, indicating that many-body interactions are beneficial in meeting the requirement of the adiabatic condition, thereby facilitating the realization of adiabatic atom−molecule conversion. This enhancement of the fulfillment of the adiabatic condition is further evidenced by the stabilization of periodic oscillations in the mean molecule number over time, protected by these interactions, even when the frequency lies within the localized regime. Interestingly, in the diffusive regime, while the many-body interaction has little effect on the dynamical equilibrium of atom−molecule conversion, it significantly expands the diffusive regime. In the high-frequency limit, many-body interactions are found to completely suppress atom−molecule conversion. Our results shed light on how molecule−molecule interactions influence the boundaries between different dynamical regimes.
Soliton molecules are fascinating phenomena in ultrafast lasers which have potential for increasing the capacity of fiber optic communication. The investigation of reliable materials will be of great benefit to the generation of soliton molecules. Herein, an all-fiber laser cavity was built incorporating carbon nanotubes-based saturable absorber. Mode-locked pulses were obtained at 1565.0 nm with a 60 dB SNR and a 4.5 W peak power. Soliton molecules were subsequently observed after increasing the pump power and tuning polarization state in the same cavity, showing variable separation of pulses between 4.87 and 25.76 ps. Furthermore, these tunable soliton molecules were verified and investigated through numerical simulation, where the tuning of pump power and polarization state were simulated. These results demonstrate that soliton molecules are promising to be applied in optical communication, where carbon nanotube-based mode-locked fiber lasers serve as a reliable platform for the generation of these soliton molecules.
