Anjan Soumyanarayanan

Altermagnets, which combine antiferromagnetic-like magnetic compensation with ferromagnetic-like broken time-reversal symmetry, hold great promise for high-density and ultrafast spintronic applications. However, the detection and switching of perpendicular altermagnetic order are fundamentally constrained by magnetic symmetry, restricting both fundamental studies and practical implementation. Here we demonstrate the robust electrical reading and deterministic switching of perpendicular altermagnetic order by designing a Dirac semimetal/altermagnet heterostructure of PtTe₂/CrSb. This engineered interface enables anomalous Hall read-out via the altermagnetic proximity effect and delivers efficient spin–orbit torque for manipulating the epitaxial perpendicular Néel vector in CrSb. These findings substantially broaden the functional scope of altermagnetic heterostructures and pave the way for scalable altermagnetic memory.

Gigahertz excitations of magnetic films are widely explored for energy‐efficient, high‐frequency microelectronics. The advent of nanoscale chiral spin textures (CSTs) with topological dynamics promises novel resonance characteristics. However, prior works on technologically relevant chiral multilayers encountered key material constraints, precluding the realization of functional CST resonances. We address this by engineering a minimally damped, strongly chiral multilayer with a robust broadband resonance spectrum. Microwave spectroscopy, Lorentz microscopy, and simulations elucidate contrasting resonance features on either side of zero magnetic field arising from distinct irreversible CST transitions. A simple analytical model can quantitatively describe these robust inter‐textural resonances over the entire field‐frequency range. Crucially, in situ CST reconfigurability enables analog tunability of the resonant dispersion ‐ with wide‐band, deterministic, non‐linear (or linear) modulation via the input knob. Our work unlocks the microwave potential of multilayer CSTs by leveraging their unique thermodynamics. It opens the door to fabrication‐free reconfigurable magnonics, toward broadband transmission and unconventional computing.

The stability and efficient electrical control of chiral spin textures (CSTs) is critical for their implementation in racetrack device architectures. Three principal properties determine the utility of material platforms for spin-texture dynamics: perpendicular magnetic anisotropy (PMA), Dzyaloshinskii–Moriya interaction (DMI), and spin Hall angle (SHA). Notwithstanding individual studies, a comprehensive benchmarking of these key interactions across racetrack-compatible material systems remains lacking. Here, we systematically evaluate tunnel-readout compatible HM/CoFeB/MgO trilayers fabricated using wafer-scale techniques. Their key properties—PMA, DMI, and SHA—were characterized across four heavy metals (Pt, W, Ta, and Ir) and two CoFeB compositions using magnetometry, spectroscopy, and transport techniques, respectively. Our results reveal that the W-based stacks exhibit robust PMA and high SHA, while the Pt-based stacks provide the strongest DMI. Notably, both DMI and SHA depend strongly on both heavy metal and CoFeB composition, underscoring the critical role of alloy engineering in controlling interfacial magnetic properties. Our work provides quantitative benchmarks and materials design principles for developing next-generation CST-based racetrack devices.

Voltage control of magnetic anisotropy (VCMA) induced by charge accumulation is typically considered as an ultrafast process, enabling energy-efficient and high-speed magnetization switching in spintronic devices. In this work, we investigate the real-time dynamics of VCMA-assisted switching of magnetic tunnel junctions via relaxation in a magnetic field. We show that device-dependent charging effects and magnetic granularity in the free layer limit the switching speed at applied voltages close to the critical switching threshold. Increasing the voltage or the applied magnetic field reduces the incubation delay and total switching time to below a few ns. Micromagnetic simulations incorporating the finite charging times of the tunnel junction and the granularity of the magnetic film reproduce the experimental results, providing critical insights into optimizing VCMA-driven magnetization control for memory and logic applications.

Voltage control of magnetic anisotropy (VCMA) induced by charge accumulation is typically considered as an ultrafast process, enabling energy-efficient and high-speed magnetization switching in spintronic devices. In this work, we investigate the real-time dynamics of VCMA-assisted switching of magnetic tunnel junctions via relaxation in a magnetic field. We show that device-dependent charging effects and magnetic granularity in the free layer limit the switching speed at applied voltages close to the critical switching threshold. Increasing the voltage or the applied magnetic field reduces the incubation delay and total switching time to below a few ns. Micromagnetic simulations incorporating the finite charging times of the tunnel junction and the granularity of the magnetic film reproduce the experimental results, providing critical insights into optimizing VCMA-driven magnetization control for memory and logic applications.

Antiferromagnetic (AF) skyrmions are topological spin structures with fully compensated, net‐zero magnetization. Compared to their ferromagnetic (FM) skyrmion counterparts, their reduced stray field and enhanced electrical response can enable linear, high‐throughput current‐driven motion. However, their bubble‐like character in conventional bilayer AFs limits their stability to fluctuations, leading to deformation and annihilation. This work presents the engineering of a composite AF chiral multilayer, wherein the interplay of AF and FM interlayer couplings generates compensated skyrmions with compact structures. High‐resolution magnetic imaging and micromagnetic simulations show that the internal exchange field stabilizes AF skyrmions at zero external field with characteristics comparable to FM counterparts at 100 mT. Quantitative analyses establish their decoupling above the exchange field, yielding independent, spatially segregated textures in constituent chiral layers. This work provides a foundation to develop AF spin‐textures with enhanced immunity, compatible with efficient readout and manipulation, with relevance to unconventional computing.

Antiferromagnetic (AF) skyrmions are topological spin structures with fully compensated, net-zero magnetization. Compared to their ferromagnetic (FM) skyrmion counterparts, their reduced stray field and enhanced electrical response can enable linear, high-throughput current-driven motion. However, their bubble-like character in conventional bilayer AFs limits their stability to fluctuations, leading to deformation and annihilation. Here we present the engineering of a composite AF chiral multilayer, wherein the interplay of AF and FM interlayer couplings generates compensated skyrmions with compact structures. High-resolution magnetic imaging and micromagnetic simulations show that the internal exchange field stabilizes AF skyrmions at zero external field with characteristics comparable to FM counterparts at 100 mT. Quantitative analyses establish their decoupling above the exchange field, yielding independent, spatially segregated textures in constituent chiral layers. This work provides a foundation to develop AF spin-textures with enhanced immunity, compatible with efficient readout and manipulation, with relevance to unconventional computing.