Logic Operations Using Spin-Orbit Torque-Driven Nanoscale Bimerons

Magnetic bimerons are nanoscale-sized topologically stable quasiparticles that have attracted recent research interest due to potential applications in next-generation spintronic devices. In this work, using micromagnetic simulations, we explore the possibility of utilizing bimerons as carriers of information and in particular for logic operations in an in-plane magnetized system. Initially, we demonstrate the ultrafast, zero-field, and in-plane bias field-assisted nucleation of isolated bimeron by locally injecting perpendicular spin currents into the magnetic track. We also study spin-orbit torque (SOT)-induced propagation of bimeron in clean ferromagnetic (FM) racetrack as a function of current density (j) and Gilbert damping (α) values. Our results indicate a linear increase in bimeron velocity with increasing strength of j. Moreover, we examine the dynamics of bimeron by incorporating geometrical constriction in the form of a semicircular notch along one edge of the FM racetrack. Depending upon the notch size and critical current density, the bimeron majorly exhibits trap, pass, and trap-pass-annihilate dynamics. We further propose a bimeron-based racetrack model that can perform both AND and OR logic operations by effectively tailoring the strength of current density for a fixed notch diameter and provide an estimate of energy expense for these operations. We believe our results are important to design energy efficient spintronic devices that can integrate multiple functionalities.