Advanced Physics Research最新文献

A polymorph of Cu₂OSeO₃ with the distorted kagome lattice is successfully obtained using the high-pressure synthesis technique (Cu₂OSeO₃-HP). The structural analysis using X-ray and neutron powder diffraction suggests that the tetrahedral Cu²⁺ clusters [similar to those in Cu₂OSeO₃ ambient-pressure phase (Cu₂OSeO₃-AP)] exist in Cu₂OSeO₃-HP but with three symmetry inequivalent sites. No structural change is observed between 1.5 K and the room temperature. The complex magnetic H-T phase diagram is established based on the temperature- and field-dependent magnetization data, indicating two distinct antiferromagnetic phases at low and intermediate temperatures, in addition to the higher-temperature spin-glass-like phase. The low temperature phase is identified by neutron powder diffraction refinements as a canted noncollinear antiferromagnetic order with a weak ferromagnetic component along the b-axis. Size of the refined ordered moment is ≈1.00(4) µ_B in Cu₂OSeO₃-HP, indicating a large enhancement compared to that of Cu₂OSeO₃-AP (≈0.61 µ_B). By applying a uniaxial stress, finite enhancement of weak ferromagnetic component in the noncollinear antiferromagnetic phase in Cu₂OSeO₃-HP is observed, which is the clear evidence of the piezomagnetic effect. Interestingly, the sign of the induced magnetization changes on heating from the low-temperature to the intermediate-temperature phases, indicating a novel piezomagnetic switching effect in this compound.

Terahertz (THz) technology has attracted significant attention because of its unique applications in biological/chemical sensing, medical imaging, non-invasive detection, and high-speed communication. Metasurfaces provide a dynamic platform for THz sensing applications, showcasing greater flexibility in design and the ability to optimize light-matter interactions for specific target enhancements, which includes enhancing the intramolecular and intermolecular vibration modes of the target biological/chemical molecules, setting them apart from conventional approaches. This review focuses on recent THz metasurface sensing methods, including metasurfaces based on toroidal dipole and quasi-bound states in the continuum to improve sensing sensitivity, nanomaterial-assisted metasurfaces for specific recognition, and metasurfaces combined with microfluidic with reduce water absorption loss. Furthermore, the applications of THz metasurface sensing is reviewed, including detecting the concentration of biomolecules, cells, tissues, and microbes, THz biomolecular fingerprint absorption spectra recognition, and identifying chiral compounds using chiral and achiral metasurfaces. Finally, the prospects for the next generation of THz sensors are examined.

Mid-infrared (Mid-IR) integrated optics has tremendous applications in spectroscopic sensing, imaging, and ranging. Compared with visible light and near-IR wavelengths, the study of mid-IR photonic integrated devices is limited due to the need for more suitable materials and designs for constructing high-performance on-chip optoelectronic devices. Integrating emerging 2D materials with novel waveguide devices opens an avenue to boost the development of high-performance optoelectronic waveguide devices operating in the mid-IR wavelength range. This review summarizes the previous progress, current status, and future trends in exploring mid-IR optoelectronic waveguide devices with 2D materials. Specifically, the authors focus on the research efforts of developing passive photonic devices, modulators, photodetectors, and light sources. Then, the challenges and prospects in this area are discussed. The paper provides a valuable reference for researchers in infrared physics, optoelectronics, integrated optics, material science, sensing, and spectroscopy.

The diverse morphologies of 2D transition metal dichalcogenides (2D TMDs) motivate their broad potential applications in the next generation of electronic, optical, and catalytic technologies. It is advantageous to develop controllable growth techniques that afford versatility through direct manipulation of the growth parameters. A fundamental understanding of the physical mechanisms driving various growth modes is crucial for achieving the process precision necessary for obtaining reproducible morphologies in 2D TMDs. Thermodynamic and kinetic considerations are two key physical strategies. Thermodynamic strategies mainly involve the manipulation of parameters like temperature and the chemical potential of precursors to ensure the thermostability of various morphologies. Conversely, kinetic strategies, focusing on the factors, like precursor diffusion, adsorption, and desorption during the growth, also enable atomic-level kinetics control of the resulting morphologies. Often, an interplay of both mechanisms drives the growth of a particular morphology. This review aims to provide an updated guidance for exploiting these physical strategies in the versatile technique of chemical vapor deposition. The opportunities for further exploring the control of these physical mechanisms are discussed through recent examples with an eye on unlocking the untapped potential of 2D TMDs in areas such as phase engineering and shape control for advanced applications.

Towards Improving Gain-Dissipative Ising Machines

The front cover illustrates the light-excited nonlinearity in defective lattices, that is, topologically defective lattice potential (TDLP) can facilitate domain clustering dynamics. In article number 2400035, Zhiqiang Liao, Munetoshi Seki, and co-workers explain how they constructed an Ising machine by using TDLP with strong damping capability. The proposed system exhibits robust and excellent performance in large-scale combinatorial optimization, even in environments where noise intensity exceeds its saturated fixed-point amplitude.

Epsilon-Near-Zero (ENZ) media have attracted widespread interest due to their unique electromagnetic properties, which have brought distinctive characteristics and phenomena, such as spatiotemporal decoupling, supercoupling and tunneling, constant phase transmission, near-field enhancement, and so on. However, these ENZ characteristics are existed in natural plasmonic materials at their intrinsic plasma frequencies and accompanied by significant losses, thus limiting their applications in engineering. Different from the effect ENZ media with artificially periodic structures, the waveguide ENZ media offers a promising platform with non-periodic architectures. Unlike the natural plasmonic materials and the periodic-structured ENZ media, the waveguide ENZ media utilizes waveguide dispersion to achieve effective ENZ characteristics and phenomena with lower loss and smaller dimensions. This review begins with an exploration of the fundamental properties of the waveguide ENZ media and then introduces the design principles of different ENZ-based electromagnetic devices. Finally, the review concludes with the challenges and potential development directions encountered by the ENZ media in the realm of electromagnetic applications.

The dynamic regulation of thermal radiation in the mid-infrared region is technologically important in diverse applications such as thermal management and camouflage. However, there is a notable lack of research on the combination of infrared radiators and memristors, which can maintain previous states or modes without extra power consumption. Here, a memristive mid-infrared radiator, where graphene nanoribbon grating serves simultaneously as a floating gate for charge storage and a tunable infrared nanoantenna for thermal radiation is proposed. This design enables precise and fast modulation, low power consumption, and scalability. Even a small change of one attocoulomb in the stored charge can produce a 1-µm peak shift in the absorption peak. This work provides a platform for a memristive infrared thermal radiator that can be further exploited for electrochromic glazing or on-chip radiative cooling.

In spin wave (SW) devices, the modulation of SWs for computational units is necessary, imposing extremely high demands on material systems. In this study, high-quality epitaxial-grown spinel γ-Fe₂O₃ thin films on conductive Nb-doped SrTiO₃ substrates, achieving fast-speed, high-frequency, and long-distance SW propagation in this ferrimagnetic material, are developed. A novel two-step film growth technique using pulsed laser deposition is proposed and optimized, and the damping constant, exchange stiffness, and anisotropies of γ-Fe₂O₃ are determined. Compared to reported semiconductor magnetic materials, these epitaxial-grown γ-Fe₂O₃ thin films exhibit a significantly lower damping constant of 10⁻², representing a substantial advancement. Using finite-difference calculations, SW propagation is simulated, and vital information on transmission distance and dispersion curves is obtained. Experimental results show excellent agreement with these simulations. By applying a voltage to both sides of the conducting substrate, current across the film and SW device, resulting in the frequency shift of the SWs, is generated. These results demonstrate that high-quality γ-Fe₂O₃ films developed through the two-step growth method can efficiently propagate SWs, offering possibilities for various modulation methods in SW-based computing devices. This study positions spinel γ-Fe₂O₃ as a promising ferrimagnetic candidate for future applications in efficient SW modulation within computational systems.

Nitrogen-vacancy (NV) centers in diamonds are one of the most promising systems for quantum technologies, including quantum metrology and sensing. A promising strategy for the achievement of high sensitivity to external fields relies on the exploitation of large ensembles of NV centers, whose fabrication by ion implantation is upper limited by the amount of radiation damage introduced in the diamond lattice. In this work an approach is demonstrated to increase the density of NV centers upon the high-fluence implantation of MeV N²⁺ ions on a hot target substrate (>550 °C). The results show that with respect to room-temperature implantation, the high-temperature process increases the vacancy density threshold required for the irreversible conversion of diamond to a graphitic phase, thus enabling to achieve higher density ensembles. Furthermore, the formation efficiency of color centers is investigated on diamond substrates implanted at varying temperatures with MeV N²⁺ and Mg⁺ ions revealing that the formation efficiency of both NV centers and magnesium-vacancy (MgV) centers increases with the implantation temperature.