Magnon scattering modulated by omnidirectional hopfion motion in antiferromagnets for meta-learning

Abstract

Neuromorphic computing is expected to achieve human-brain performance by reproducing the structure of biological neural systems. However, previous neuromorphic designs based on synapse devices are all unsatisfying for their hardwired network structure and limited connection density, far from their biological counterpart, which has high connection density and the ability of meta-learning. Here, we propose a neural network based on magnon scattering modulated by an omnidirectional mobile hopfion in antiferromagnets. The states of neurons are encoded in the frequency distribution of magnons, and the connections between them are related to the frequency dependence of magnon scattering. Last, by controlling the hopfion’s state, we can modulate hyperparameters in our network and realize the first meta-learning device that is verified to be well functioning. It not only breaks the connection density bottleneck but also provides a guideline for future designs of neuromorphic devices.

Orbitronics: light-induced orbital currents in Ni studied by terahertz emission experiments

“…For two-dimensional electron gases at Rashba interfaces and the surfaces or interfaces of topological insulators, the charge-to-spin conversion is usually named the spin Rashba-Edelstein effect 7 – 10 . In ferromagnet (FM)/nonmagnet (NM) heterostructures, the spin currents induced by spin Hall effect or spin Rashba-Edelstein effect are strong enough to reverse the magnetization of the FM material by spin-orbit torque 11 – 20 . Therefore, both spin Hall effect and spin Rashba-Edelstein effect have attracted much attention due to their technological significance in developing future magnetic memory devices.…”

Engineering Symmetry Breaking Enables Efficient Bulk Spin‐Orbit Torque‐Driven Perpendicular Magnetization Switching

“…Current-induced spin-orbit torque (SOT) effect has attracted considerable attention for efficient control of magnetic order, which is promising for the application of nonvolatile, low-power, and high-density magnetic memory, and spin logic. [1][2][3][4][5][6][7] The SOT-driven perpendicular magnetization switching is usually studied in nonmagnetic/ferromagnetic (NM/FM) bilayers. [8,9] For the purpose of making SOT switching a feasible technology, the SOT-based devices are required to show high thermal stability and low switching current density (J c ) simultaneously.…”

Magnetic hopfion rings entangled with skyrmions

“…Reporting in Nature, 4 Zheng and colleagues demonstrate the diversity of the hopfion rings entangled with skyrmion strings in FeGe, a skyrmion-hosting magnetic material. Using advanced microscopes and simulations, the team shows that these hopfion rings can be reliably nucleated in a confined sample via a specific protocol called 'field-swapping'.…”

“…The red and cyan lines represent the equi-spin lines of magnetizations with their x-component equal to +1 and -1, respectively. (B) Field-swapping protocol to create a hopfion ring, adapted from Zheng et al 4 . Surfaces where the magnetizations with their z-components equal to 0 (first, second, and fourth panel) and 0.5 (third panel) are plotted.…”