Separating the momentum-space intrinsic Berry-curvature contribution to the anomalous Hall conductivity (AHC) from domain-mediated and extrinsic contributions in bulk ferromagnetic Weyl semimetals remains a central challenge. We address this via contact engineering in a ∼670 μm thick Co3Sn2S2 single crystal, where deep Ohmic contacts promote depth-distributed current flow without perturbing the bulk. Above ∼0.3 T, a single- or few-domain state exposes the intrinsic Berry-curvature response, with Callen–Callen scaling Ku/Ku(0)=[M/M(0)]n=2.258 holding below 120 K. Above 120 K, domain multiplication weakens the exchange splitting and magnetocrystalline anisotropy Ku, driving a sharp σxy crossover near 125 K. In low-field zero-field-cooled multidomain states, real-space Berry curvature and moderate extrinsic contributions sustain the Hall response up to ∼140 K. These results establish contact engineering as a noninvasive route for cleanly separating intrinsic from domain-mediated AHC in thick Weyl semimetal crystals.
Indium-rich amorphous oxide semiconductors exhibit high electron mobility, but oxygen vacancy (Vo) related donors often cause a negative threshold voltage (Vt) and bias-stress instability. This work demonstrates a 2 nm InRuZnO (IRZO) interlayer into an InZnO (IZO) channel as an internal oxygen-affinitive layer, rather than as a conventional bulk dopant. The IZO/IRZO/IZO tri-layer thin-film transistor (TFT) exhibits a field-effect mobility of 31 cm2/V s, a Vt of 0.3 V, a forward–reverse hysteresis below 100 mV, and an ON/OFF current ratio of 4 × 108. X-ray photoelectron spectroscopy depth profiling of the O 1s reveals a Ru-modulated vertical distribution of Vo, with Vo concentrations of 32%, 20%, and 24% in the top IZO, IRZO, and bottom IZO regions, respectively. This depth dependence indicates that the Ru-containing interlayer locally stabilizes oxygen bonding and redistributes Vo across the In-rich channel. The tri-layer TFTs also reduce the ΔVt to −0.3 V after 1000 s of negative gate-bias stress at −2 MV/cm, demonstrating improved reliability. This work identifies Ru-mediated Vo modulation as a route for improving the mobility–stability balance of sputtered In-rich oxide TFTs.
Atomically thin semiconductor films grown by metal organic chemical vapor deposition (MOCVD) will be crucial for the integration of two-dimensional (2D) materials into semiconductor devices produced at scale. However, the development of wafer-scale growth techniques has outpaced the development of corresponding metrology to assess film quality of 2D transition metal dichalcogenide (TMD) films. One particularly difficult issue is that the stacking sequence when overgrowing TMD films is not uniquely defined, with different possible orientations for the second layer. Determining this stacking order of individual grains when growing additional layers over a closed monolayer is an outstanding challenge for such films. Here, we use second harmonic generation (SHG) microscopy to assess the size, dispersion, and stacking orientation of bilayer grains in MOCVD-grown MoS2 films. We correlate several microscopy techniques—bright-field white-light microscopy imaging, atomic force microscopy, photoluminescence mapping, and SHG microscopy—to show that SHG can uniquely map the stacking orientation of bilayer nucleates in these films. We expect this to drive the development of further metrology based on SHG for semiconductor applications, especially in the development of 2D material specific tools.
Electric-field control of spintronic terahertz (THz) emitters offers an attractive route toward compact and integrated THz devices. However, the quantitative relation between electric field and magnetic field orientation in dual manipulation of THz polarization remains unclear. Here, we investigate THz emission from Pt/Ni bilayers on ferroelectric Pb(Mg1/3Nb2/3)O3-PbTiO3 substrate. Rotated magnetic-field-dependent THz emission measurements, combined with a Stoner–Wohlfarth macrospin analysis, quantitatively determine the voltage-dependent anisotropy fields and their orientations. By experimentally comparing the vectorial THz response at representative magnetic-field orientations, we achieve an appreciable electric-field control of THz polarization rotation of up to 78° at a magnetic field angle of θH = 90°. Utilizing this polarization manipulation at the optimized magnetic field angle, we propose an electrically encoded THz far-field imaging scheme via delayed two-pulse excitation. These results provide a new approach for electrically designing structured THz emission.
This work characterizes the conventional and rotating magnetocaloric effect (RMCE) present in a 0.27 mm-thin plate of hydrogenated La(Fe,Mn,Si). The high aspect ratio (∼50) of the thin plate leads to an anisotropic magnetocaloric effect (MCE), dependent on the relative orientation of the external magnetic field, and an RMCE when the external field is rotated. We find a maximum rotating adiabatic temperature change (ΔTadrot) of 1.17 K upon rotation of a 1 T magnetic field, and 1.12 K with 0.6 T—a reduction of only 4% for a 40% reduction in field strength. Magnetostatic computations revealed a considerable rotating entropy change (ΔSisorot), comparable to the MCE of Gd for similar fields, reaching 3.97 J K−1 kg−1 for 1 T and 3.68 J K−1 kg−1 for 0.6 T (7% reduction), highlighting La-Fe-Mn-Si alloys as high potential candidates for a magnetic refrigerator based on the RMCE utilizing low magnetic fields.
Active control of heat flow at the nanoscale is important for next-generation thermal management and spintronic devices. Here, we report a substantial magnetic modulation of the in-plane lattice thermal conductivity (κL) in monolayer Fe3GaTe2, a two-dimensional van der Waals metal with room-temperature ferromagnetism. Using first-principles transport calculations combined with the special quasirandom structure approach, we demonstrate that the room-temperature κL decreases from 28.94 W m−1 K−1 in the ferromagnetic state to 5.09 W m−1 K−1 in the paramagnetic phase, yielding an intrinsic lattice thermal switching ratio of ∼5.7. Even when accounting for electronic thermal contributions, an estimated total magneto-thermal switching ratio of ∼3.5 is maintained. This massive reduction in κL fundamentally originates from spin-disorder-induced symmetry breaking. In the ferromagnetic state, the out-of-plane flexural acoustic (ZA) mode dominates the lattice heat conduction due to strict selection-rule protection. Upon transition to the paramagnetic phase, localized magnetic disorder destroys the horizontal mirror symmetry (σh), unlocking strong anharmonic scattering channels. This severely suppresses the ZA mode, drastically reducing its relative thermal contribution, and induces a crossover to longitudinal-acoustic-dominated transport. Our findings demonstrate the viability of regulating lattice heat transport via microscopic spin-lattice coupling, providing a quantitative framework for advanced thermal routing and spin-caloritronics.
Van der Waals (vdW) interaction plays a central role in the construction of mass in nature, based on which heterostructure materials are highly versatile and can be designed with distinctive functions. In this work, using molecular dynamics simulations, we show that a simple vdW heterostructure consisting of carbon nanocones (CNCs) encapsulating a fullerene molecule demonstrates surprising water diode behavior, which is not found in existing nanochannels. Owing to the strong vdW interaction of fullerene–CNC, the fullerene will be stuck near the CNC tip, resulting in a closed state for water transport in the convergent pressure direction. Nonetheless, when the divergent pressure exceeds certain critical values, the CNC channel opens for water transport, where the critical pressure is sensitive to the fullerene size and shape. This diode behavior originates from coupled fullerene–water dynamics: the water-driven force competes with the fullerene–wall vdW attraction to determine the fullerene position and stability inside the CNC. Notably, both the fullerene size and orientation modulate the vdW interaction barrier; in particular, an ellipsoid C80 fullerene reorients toward a preferred tilt angle relative to the CNC axis, which alleviates hindrance and sustains efficient tip-to-base water transport. These results establish fullerene encapsulation as a compact vdW-gating strategy for designing high-performance CNC-based water diodes.
MXene materials hold great promise for flexible pressure-sensing applications; however, the evolution of their carrier transport and energy relaxation processes under external pressure remains poorly understood. In this work, we systematically investigate the photoexcited ultrafast dynamics of the prototypical MXene Ti3C2Tx under hydrostatic pressures ranging from 0.7 to 6.4 kbar. Our results reveal that with increasing pressure, the relaxation of the excited-state absorption peak centered at ∼520 nm is significantly retarded, manifested by a monotonic increase in both the electron–electron scattering time (τ1) and the electron–phonon scattering time (τ2). The counterintuitive pressure-induced slowdown of carrier relaxation finds its origin in the synergistic effects of enhanced inter-flake charge hopping, reduced carrier densities, and weakened electron–phonon coupling. Furthermore, the accelerated relaxation of the plasmon bleach peak with increasing pressure provides direct evidence for improved lattice cooling efficiency due to weakened electron–phonon coupling and enhanced interlayer thermal diffusion. Collectively, our findings establish a microscopic physical picture of pressure-modulated interlayer coupling and ultrafast dynamics in MXenes, offering new experimental benchmarks and providing a microscopic foundation for the understanding of pressure-sensing mechanisms in MXene-based devices.
Ultraviolet (UV) photodetectors based on zinc oxide (ZnO) wide-bandgap semiconductors have been intensively explored for applications in environmental monitoring, optical communication, and biosensing. However, conventional ZnO-based photodetectors often suffer from limited responsivity and relatively slow photoresponse speeds, which severely restrict their practical applications. Herein, we report a highly sensitive and fast-responsive photodetector based on ZnO/MgZnO core–shell radial-heterostructured nanowires (NWs) through radial interface engineering. The introduction of a wider bandgap MgZnO shell onto ZnO NWs forms a radial ZnO/MgZnO heterojunction, which introduces a built-in electric field that effectively promotes the separation and collection of photogenerated carriers. The optimized device exhibits a fast response time of 0.41/2.30 s (rise/decay) and a high responsivity of 0.75 A/W at zero bias. Furthermore, this study reveals a nonlinear relationship between the MgZnO shell thickness and the photoresponsivity of the device, and identifies the optimal MgZnO shell thickness for optimizing device performance. These results demonstrate that core–shell heterointerface engineering is an effective strategy for balancing responsivity and response speed in ZnO-based UV photodetectors.
Gallium oxide (Ga2O3) vertical transistors are promising for next-generation high-voltage power electronics, yet achieving normally-off operation remains challenging due to insufficient electrostatic depletion of the surface channel and severe gate-edge electric-field crowding. Here, we demonstrate a controlled transition from depletion-mode to enhancement-mode operation in all-ion-implanted planar-gate β-Ga2O3 current-aperture vertical electron transistors, a gate region-damage-minimized architecture that avoids gate-trench etching. A multi-step nitrogen-graded current-blocking layer (CBL) simultaneously engineers channel electrostatics and high-voltage electric-field distributions by introducing vertically distributed charge compensation. This graded profile enhances subsurface channel depletion, suppresses parallel conduction, and redistributes the peak electric field from the gate edge toward the buried CBL. As a result, the enhancement-mode device achieves a threshold voltage of 4.17 V, a breakdown voltage of 1310 V, a specific on-resistance of 19.1 mΩ cm2, and an ultralow threshold hysteresis of 52 mV. These results establish nitrogen-graded electrostatic compensation as an effective strategy for simultaneously realizing normally-off operation and enhanced voltage-blocking capability in vertical β-Ga2O3 transistors.
The photovoltaic performance of ZnSnN2 homojunction has never been studied. Here, ZnSnN2 homojunction solar cells with Ag-doped ZnSnN2 as the p-type layer are fabricated with magnetron sputtering deposition, and the mechanism limiting the photovoltaic performance is revealed. The junction is abrupt. The current transport is dominated by thermionic emission below 320 K and generation-recombination (GR) in the space charge region in 330–380 K. Below 320 K, the short circuit current density and the open circuit voltage are limited by nonradiative interface recombination. The open circuit voltage loss also results from interfacial barrier height inhomogeneity, which obeys the Gaussian distribution model or the temperature fluctuation of interface barrier heights for holes. At higher temperatures, deep energy levels in the middle of the bandgap result in the GR in the space charge region. One shallow energy level at 0.13 eV and one interface energy level at 0.72 eV above the valence band maximum are observed. The former is likely induced by substitutional Ag-doping.
To enable an intuitive, rapid, and universal evaluation of the structural stability of body-centered-cubic (bcc) refractory alloys, we propose the “band-filling stability index” (BFSI) derived from the electronic density of states. We establish a correlation between BFSI and structural stability, showing that BFSI = 0.00 corresponds to maximum stability, whereas BFSI < 0.00 indicates reduced stability. The electronic origin of stability under varying BFSI conditions lies in the deviation of Fermi level from the pseudogap bottom. The modified BFSI captures a complex, non-linear dependence of stability on valence electron concentration (VEC), whereas the previous fraction of occupied bonding states (gocc/gbond) holds a simple linear relationship only in the low VEC range. The identified relationship between BFSI and VEC enables point-to-point stability prediction, bypassing conventional computation-intensive high-throughput screening methods. Furthermore, we find that enhanced stability is often accompanied by reduced ductility, consistent with existing experimental observations. The universality and reliability of our findings are rigorously validated across diverse bcc refractory alloys. This work provides a universal, electronic-structure-driven paradigm for efficiently exploring high-stability bcc refractory alloys.
We report on the experimental realization of a magnonic XNOR logic gate based on a nonlinear Mach–Zehnder interferometer (MZI) with yttrium iron garnet waveguides in both arms. Information in input data streams is translated into an equivalent sequence of π-phase jumps induced through the nonlinear mechanisms in continuous spin-wave signals propagating in different arms of the MZI. Constructive/destructive interference at the output combiner produces the signal corresponding to the targeted XNOR logical function. The performance characteristics of the logic gate are discussed based on the developed ad hoc theory of the nonlinear processes involved.
Ensemble nitrogen-vacancy (NV) centers enable vector magnetic-field sensing, but the tetrahedral symmetry of the four NV orientations renders the field direction intrinsically ambiguous in ensemble optically detected magnetic resonance (ODMR) measurements. For a fixed field magnitude, up to 48 symmetry-related orientations can produce identical spectra. Here, we introduce a double-rotation protocol that resolves this symmetry-induced ambiguity without applying bias magnetic fields or other symmetry-breaking perturbations. By comparing reconstructed field directions obtained from ODMR spectra before and after two controlled rigid rotations about orthogonal axes, the protocol geometrically restricts the solution space to a unique angular region up to the intrinsic inversion symmetry B↔−B. The method is purely geometric and independent of the specific magnetic-field reconstruction algorithm. It is particularly suited for moderate magnetic fields (from a few millitesla to a few tens of millitesla) and for experimental situations where additional bias fields would perturb the magnetic system under investigation.
Amorphous Ga-Zn-O (a-GZO) thin films were synthesized via atomic layer deposition (ALD) and subsequently processed using laser annealing (LA) techniques. The investigation demonstrates that the films maintain their amorphous state across varying laser irradiation energy intensities. This study systematically evaluates the modulation of microstructure, oxygen vacancy (Vo) concentration, and optoelectronic properties induced by LA. Results indicate that as the laser energy intensity increases, the Vo content rises from 22.4% to 40.63%. An optimal Vo concentration is found to trigger trap-assisted gain, significantly enhancing the photoresponsivity of the device; however, excessive Vo leads to a surge in the dark current and a degradation of device uniformity. The film treated at 0.3 J/cm2 exhibits the most superior comprehensive performance, achieving a field-effect mobility of 9.6 cm2/V s and an on/off ratio of 106, while demonstrating improved uniformity and stability. Furthermore, the TFT-based photodetector achieves an ultrahigh responsivity (R) of 235.42 A/W under 0.02 mW/cm2 of 310 nm ultraviolet (UV) illumination. This work highlights the dual advantages of amorphous oxide thin films in maintaining high uniformity while achieving ultrasensitive UV detection.
The extraction of intrinsic spin-wave damping and group velocity in a micro-structured yttrium iron garnet (YIG) device from direct transmission signals can be complicated by near-field inductive and capacitive coupling from closely spaced coplanar waveguide (CPW) antennas. In this work, we investigate a micrometer-sized YIG device and observe MHz-scale spectral ripples in its continuous-wave transmission spectra whose periodicity disperses with the applied magnetic field. We demonstrate that by performing time-domain transformations of broadband S-parameters, these ripples can be explicitly decoded as coherent spin-wave echoes originating from edge reflections. Because the echo wave-packet travels a significantly longer path than the direct signal, it effectively decouples from the CPW near-field feedthrough, stabilizing into a propagating magnon mode. Without the need for additional probes, we extract a relaxation time of τ≈50 ns and an effective Gilbert damping constant of α exp ≈8×10−4, while directly resolving group velocities that agree well with theoretical predictions where direct short-distance measurements deviate. Furthermore, reflection spectroscopy independently supports the origin of these signals. These observations are further corroborated by micromagnetic simulations. Our work establishes a robust protocol for magnon-based metrology, demonstrating how boundary effects can be utilized for on-chip delay elements.
Accurate prediction of the output acoustic power of an ultrasonic therapy system is critical to treatment safety and efficacy. Here, we systematically verify the accuracy of a system-level Krimholtz–Leedom–Matthaei power model that fully integrates the driving source, cable and tuning network, power ultrasonic transducer, and acoustic load using the transmission matrix method. Validated in three representative power transducers made of PZT-4 ceramic, PZT-4 composite, and PZT-5H ceramic up to an intensity-on-transducer-surface (ITS) of 21.5 W/cm2, the model achieves relative errors of only −6% to −10% without requiring nonlinear material parameters, a value limited by the current measurement setup rather than by the model's inherent capability. Moreover, a counterintuitive threshold effect was discovered: for thickness mode power transducers, once the mechanical quality factor Qm exceeds ∼90, further increase yields negligible gain in output efficiency. This finding provides new design guidelines for the selection of piezoelectric materials in high-power applications, showing that chasing ultrahigh Qm is unnecessary beyond this saturation point.
We present a low-cost approach to reconstructive spectrometry using arrays of commercial light-emitting diodes (LEDs). Unlike existing systems that require expensive custom-made components, our method operates LEDs in photovoltaic mode to reconstruct spectral information. A key aspect is the use of temperature as a tuning parameter to boost reconstruction accuracy. This proof-of-concept enables the development of accessible spectrometers for portable field applications, which could be particularly relevant in agriculture and the food industry.
