Qiang Zhang

Planar surface plasmon polaritons (SPPs) at metal–oxide–semiconductor (MOS) interfaces are central to plasmon‐assisted optoelectronic and tunneling devices, where ultrathin dielectrics govern field confinement and energy transfer. However, a direct link between electron energy‐loss spectroscopy (EELS) measurements and electromagnetic power dissipation at buried interfaces remains unclear. Here, we combine STEM–EELS with full‐wave electromagnetic simulations to investigate SPP excitation in planar and stacks with 10 nm dielectric spacers. Using a finite‐difference time‐domain approach, the fast electron is modeled as a broadband electromagnetic source, enabling decomposition of extinction into absorbed and scattered power and direct comparison with EEL spectra. We show that extinction is dominated by non‐radiative absorption, confirming that the observed resonances originate from SPPs confined to the buried Au–oxide interface. Increasing dielectric permittivity induces a redshift and modifies modal confinement, while losses remain Au‐dominated. Kramers–Kronig analysis and simulations further confirm dielectric dispersion effects and exponential evanescent decay across the oxide layer.

Magnetic tunnel junctions with voltage-controllable telegraphing between the parallel and antiparallel states were combined with hybrid circuits to create probabilistic bit modules. The time-dependent behavior was measured both when these devices were free running and when they were coupled together to form stochastic logic gates. Two modules were used to create a nearly deterministic NOT gate. A stochastic AND gate was demonstrated using a combination of three modules, and a statistical preference for microstates consistent with the AND gate truth table was observed. A metric is proposed for quantifying the performance through pairwise comparison of microstate probabilities.

Interfacial scattering plays a critical role in the magneto-transport properties in thin films, especially ultrathin films. In this work, we prepared [Fe(20 Å)/MgO(t)]20 multilayers with different MgO thickness t to study the interfacial scattering effect on the anomalous Hall effect. As t increases, MgO initially forms dots/flakes, which gradually connect to form continuous layers. Both longitudinal resistivity and anomalous Hall resistivity increase with MgO thickness until the MgO layers become continuous. The intrinsic, skew-scattering, and side-jump contributions to the AHE were extracted from the data. The intrinsic mechanism dominated the AHE in Fe/MgO multilayers.

Nickel‐copper‐zinc (NiCuZn) spinel ferrites have attracted intensive research owing to their unique magnetic properties and low co‐fire temperature. Combustion synthesis has been viewed as a promising protocol for the large‐scale fabrication of NiCuZn spinel ferrites. However, the spinel ferrites prepared by this method usually suffer from limited saturation magnetization and high coercivity due to their large size, which will impose detrimental harmonics on electrical equipment (e. g., transformer, motor, etc.). To address these issues, highly porous NiCuZn spinel ferrite hierarchies were prepared within several hours through a modified solution combustion method, using glucose and ammonium nitrate as the fuel and combustion enhancer, respectively. The as‐obtained NiCuZn spinel ferrite hierarchies show excellent magnetic properties with a high saturation magnetization up to 62.61 emu/g and a low coercivity of 9.6 Oe thanks to the rational distribution of cations and grain size. More importantly, this method also allows various modifications (heteroatom doping) and large‐scale applications, which may be promising for the fabrication of high‐performance soft magnets for electrical equipment.

The angle dependence of field-induced switching was investigated in magnetic tunnel junctions with in-plane magnetization and a pinned synthetic antiferromagnet reference layer. The 60 × 90 nm² elliptical nanopillars had sharp single switches when the field was applied along the major axis of the ellipse, but even with small (20°) deviations, reversal occurred through an intermediate state. The results are interpreted with a model that includes the external applied field and the effective fields due to shape anisotropy and the fringe field of the synthetic antiferromagnet and used to extract the magnetization direction at various points in the magnetoresistance loop. The implications for faster spintronic probabilistic computing devices are discussed.

Magnetic skyrmions are topological spin textures holding great potential as nanoscale information carriers. Recently, skyrmions have been predicted in antiferromagnets, with key advantages in terms of stability, size, and dynamical properties over their ferromagnetic analogs. However, their experimental demonstration is still lacking. Here, we show the imprint from ferromagnetic skyrmions into a thin film of an IrMn antiferromagnet, at room temperature and zero external magnetic field, using exchange-bias. Using high-spatial-resolution x-ray magnetic circular dichroism photoemission electron microscopy (XMCD-PEEM), we observed the imprinted spin textures within the IrMn from the XMCD signal of the uncompensated Mn spins at the interface with the ferromagnet. This result opens up a path for logic and memory devices based on skyrmion manipulation in antiferromagnets.

The excitation of Weyl semimetals obeys the relativistic Weyl equation and attracted significant research attention due to its unique electronic state. In this paper, we present an emerging approach for modulating the electron state of half-Heusler GdPtBi by hydrostatic pressure. Through measurements of the temperature-dependent resistivity and magnetoresistance (MR), a phase transition from a Weyl semimetal to a semiconductor state was identified at about 2.0 GPa upon increasing the hydrostatic pressure. Electron transport in semiconductive GdPtBi is found to be well describable by Mott variable-range-hopping. The simulated electronic structures under different hydrostatic pressures further indicate that changes in the electronic states of atoms in the primary unit cell result in a phase transition in GdPtBi. This work presents an effective strategy for modulating the electronic state by tuning the lattice constant.

The strain tunable exchange bias has attracted much attention due to its practical applications in flexible and wearable spintronic devices. Here, the flexible epitaxial NiMn/γ′-Fe₄N bilayers are deposited by facing-target reactive sputtering. The maximum strain-induced change ratios of exchange bias field H_EB and coercivity H_C (|ΔH_EB/H_EB| and |ΔH_C/H_C|) are 51% and 22%, respectively. A large strain-induced |ΔH_EB/H_EB| appears in a thicker ferromagnetic layer, but a large |ΔH_C/H_C|) appears in a thinner ferromagnetic layer. At a compressive strain, the antiferromagnetic anisotropy of the tetragonal NiMn layer increases, resulting in an increased H_C of NiMn/γ′-Fe₄N bilayers. The bending-strain induced changes of anisotropy magnetoresistance and planar Hall resistance are also observed at low magnetic fields. The bending-strain tailored magnetic properties can be ascribed to the distributions of ferromagnetic and antiferromagnetic anisotropies.

The lattice structures of epitaxial Fe₃O₄ films deposited on MgO were studied systematically using polarized Raman spectroscopy as a function of film thickness, where interesting phenomena were observed. Firstly, the spectral conflict to the Raman selection rules (RSRs) was observed under cross-sectional configuration, which can be attributed to the tetragonal deformation in the growth direction due to the lattice mismatch between Fe₃O₄ and MgO. Secondly, the blue shift and broadening of Raman peaks evidenced the decrease of the tensile strain in Fe₃O₄ films with decreasing thickness. Thirdly, distinct from the other Raman modes, the lowest T _2g mode exhibited asymmetric lineshape, which can be interpreted using the spatial correlation model. The increased correlation length introduced in the model can well explain the enhanced peak asymmetry feature with decreasing thickness. These results provide useful information for understanding the lattice structure of epitaxial Fe₃O₄ film.