Spontaneous creation and annihilation dynamics of magnetic skyrmions at elevated temperature

Funding Information: The atomistic simulations were undertaken on the VIKING cluster, which is a high performance computing facility provided by the University of York. We are grateful for computational support from the University of York High Performance Computing service, VIKING, and the Research Computing team. The work of A.D. and L.S. was supported by the Ministry of Innovation and Technology and the National Research, Development and Innovation Office under Projects No. PD134579 and No. K131938, as well as within the Quantum Information National Laboratory of Hungary. Publisher Copyright: © 2021 American Physical Society.Skyrmions are topologically protected nanoscale magnetic structures with a wide range of potential applications. Here we determine the life cycle of skyrmions from their creation to their intrinsic dynamics and thermal stability to their eventual thermodynamic demise. Using atomistic simulations of Ir/Co/Pt, parameterized from ab initio calculations, we demonstrate the thermal phase transition to a skyrmion state under application of a perpendicular magnetic field. The created skyrmions exhibit Brownian particlelike dynamics driven by the underlying thermal spin fluctuations. At an elevated temperature window well below the Curie temperature, the skyrmions are metastable and can collapse to a uniform magnetic state. With application of an external magnetic field, the intrinsic local thermal spin fluctuations at this elevated temperature window are sufficiently large to allow the spontaneous formation of new skyrmions in thermodynamic equilibrium analogous to a spontaneous skyrmion gas. Such a system could be used to implement a skyrmion-based true random number generator.Peer reviewe