Monopole Traps for Position-Based Information Coding

Abstract

We propose a spin-ice-based heterostructure capable of encoding magnetic monopole quasiparticle positions for non-volatile information storage applications. Building upon two-dimensional magnetic monopole gases formed at the interface between 2-in-2-out spin ice and all-in-all-out antiferromagnetic pyrochlore iridate, the design introduces a 3-in-1-out/1-in-3-out fragmented barrier layer into the spin-ice matrix, defining two energetically stable monopole traps. The occupancy of these traps can be deterministically controlled by an externally applied magnetic field. Monte Carlo simulations reveal robust bistable switching, thermal stability below 0.22 K, and fully reversible field-driven transitions, demonstrating the system's potential for reliable, repeatable memory operation. Crucially, the heterostructure exhibits emergent ferromagnetism linked to monopole position, enabling non-destructive readout of the memory state via spatially resolved magnetic imaging. Unlike topological carriers such as skyrmions, monopoles confined at the sub-nanometer scale offer three orders of magnitude higher information density. These results establish these monopole-trap heterostructures as a scalable platform for next-generation ultra-compact memory technologies.