Exploiting random phenomena in magnetic materials for data security, logics, and neuromorphic computing: Challenges and prospects

Random phenomena are ubiquitous in magnetism. They include, for example: the random orientation of magnetization in an assembly of non-interacting isotropic magnets; arbitrary maze domain patterns in magnetic multilayers with out-of-plane anisotropy, random polarization, and chirality of an array of magnetic vortices; or Brownian skyrmion motion, among others. Usually, for memory applications, randomness needs to be avoided to reduce noise and enhance stability and endurance. However, these uncontrolled magnetic effects, especially when incorporated in magnetic random-access memories, offer a wide range of new opportunities in, e.g., stochastic computing, the generation of true random numbers, or physical unclonable functions for data security. Partial control of randomness leads to tunable probabilistic bits, which are of interest for neuromorphic computing and for new logic paradigms, as a first step toward quantum computing. In this Perspective, we present and analyze typical materials that exhibit stochastic magnetic phenomena and we show some examples of emerging applications. The current challenges in terms of material development, as well as new strategies to tune stochasticity, enhance energy efficiency, and improve operation speeds are discussed, aiming to provide new prospects and opportunities in this compelling research field