Advanced Physics Research最新文献

A comprehensive modeling approach for elucidating the intricacies of electro-optic (EO) sampling is presented, which fully encapsulates the EO sampling process by accounting for all linear and second-order nonlinear optical effects. The developed approach implements a multi-step procedure, involving a vectorial-field modeling of the second-order nonlinear interactions occurring within the EO crystal, followed by a theoretical evaluation of the subsequent optical EO sampling components. To assess the efficacy of the approach, it is used for the sampling of terahertz electric fields (<1–>60 THz) within the bulk crystals of ZnTe and LiNbO₃, as well as a ZnTe-based waveguide. Nonetheless, this versatile method enables the investigation of EO sampling within any crystal incorporated within any geometry. This model provides a powerful tool for the in-depth exploration of EO sampling, paving the way for advancements in various applications.

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.

The thermal properties of semimetal Ta₂PdSe₆ are studied, which exhibits a large thermoelectric power factor at low temperatures, by combining chemical substitution, transport measurements, and inelastic X-ray scattering. A serious violation of the Wiedemann-Franz law (WFL) is observed, which establishes the relationship between conductivity and thermal conductivity of metals. This violation leads to a thermal conductivity of Ta₂PdSe₆ lower than expected from the WFL and resistivity below 20 K, resulting in the highest figure of merit below 20 K among the p-type thermoelectric materials thus far. Furthermore, electric and thermal resistivity show a non-Fermi liquid-like temperature dependence, indicating an exotic electronic state with an unconventional scattering process for heat and charge carriers. This study suggests that semimetals in the non-Fermi liquid regime may be an intriguing platform, not only for fundamental physics but also for exploring novel thermoelectric materials tailored for low-temperature applications.

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.

Time-varying metasurfaces have recently emerged as a promising platform to observe exotic wave behaviors in space-time systems. In this paper, it theoretically reveals invariant susceptibility parameters for perpendicular-moving metasurface. Duality-matching condition is derived by utilizing generalized sheet transition conditions (GSTCs) combined with Lorentz transformation (LT). A metasurface that satisfies the duality-matching condition can hold its susceptibility parameters when it moves perpendicularly toward the sources. The moving-invariant behavior is further discussed in time-varying media and additional reflection is found to be inevitable if the constitutive parameters is discrete in time.

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.

2D van der Waals (vdW) magnets with layer-dependent magnetic states and/or diverse magnetic interactions and anisotropies have attracted extensive research interest. Despite the advances, a notable challenge persists in effectively manipulating the tunneling anisotropic magnetoresistance (TAMR) of 2D vdW magnet-based magnetic tunnel junctions (MTJs). Here, this study reports the novel and anomalous tunneling magnetoresistance (TMR) oscillations and pioneering demonstration of bias and gate voltage controllable TAMR in 2D vdW MTJs, utilizing few-layer CrPS₄. This material, inherently an antiferromagnet, transitions to a canted magnetic order upon application of external magnetic fields. Through TMR measurements, this work unveils the novel layer-dependent oscillations in the tunneling resistance for few-layer CrPS₄ devices under both out-of-plane and in-plane magnetic fields, with a pronounced controllability via gate voltage. Intriguingly, this study demonstrates that both the polarity and magnitude of TAMR in CrPS₄ can be effectively tuned through either a bias or gate voltage. The mechanism behind this electrically tunable TAMR is further elucidated through first-principles calculations. The implications of the findings are far-reaching, providing new insights into 2D magnetism and opening avenues for the development of innovative spintronic devices based on 2D vdW magnets.