Uncovering multi-channel magnetic hopfion annihilation via a single-node, billion-spin-scale atomistic framework

2026-05-25

AI Summary

Large-scale three-dimensional magnetic texture simulations are hindered by the repeated evaluation of Hamiltonian terms in conventional atomistic spin methods. This work proposes SpinX, a GPU-native framework implemented in JAX that integrates dense, sparse, and FFT-based convolutions, pairwise list evaluations, reciprocal-space long-range dipolar field computation, and mixed-precision time propagation. It further introduces a multi-channel tensor convolution based on lattice substructure decomposition, enabling unified treatment of both regular and irregular magnetic systems. The framework achieves a peak throughput exceeding 10 billion spin updates per second on a single accelerator and supports simulations of over one billion atoms on a single node. Using SpinX, the study reveals for the first time two competing annihilation pathways for magnetic hopfions: axial collapse and lateral rupture.

Abstract

Modern atomistic spin simulations combine long stochastic trajectories, thermodynamic sampling, static optimization and multi-image transition-path workflows, all of which rely on repeated evaluation of spin Hamiltonians and become computationally prohibitive on the large lattices required for three-dimensional magnetic textures. We introduce SpinX, a GPU-native atomistic spin simulation framework built around a unified Hamiltonian interface and multiple user-selectable computational backends. Its core is a crystallographic sublattice decomposition that reformulates translationally invariant spin interactions as multi-channel tensor convolutions, enabling dense, sparse and FFT-based convolution backends, while irregular systems are handled by pair-list evaluation and long-range dipolar fields by reciprocal-space FFT. Implemented in JAX, SpinX supports deterministic and stochastic Landau-Lifshitz-Gilbert dynamics, Monte Carlo sampling, static optimization, dynamical spectroscopy and string and geodesic nudged elastic band transition-path calculations on heterogeneous accelerator platforms. A validated mixed-precision mode combines fp32 field evaluation with fp64 spin-state propagation. We validate SpinX against analytical single-spin dynamics, finite-size thermodynamics of bcc Fe and transverse dynamic structure factors. Performance benchmarks show peak throughput exceeding 10 billion spin-site operations per second on a single accelerator and aggregate single-node workloads of over 1 billion atomic spins. Applying this framework to an exchange-stabilized magnetic hopfion, we uncover two competing annihilation channels on a million-spin atomistic lattice: a previously reported axial-collapse pathway and a distinct lateral-rupture pathway with a different transition morphology and activation barrier.(Due to arXiv's limit, the abstract shown here is a shortened version)

Problem

• magnetic hopfion
• atomistic spin simulation
• multi-channel annihilation
• large-scale lattice
• three-dimensional magnetic textures

Innovation

• atomistic spin simulation
• multi-channel tensor convolution
• GPU-native framework
• magnetic hopfion annihilation
• mixed-precision dynamics