Topology of a Driven 2D Spin Torque Oscillator Array

Arrays of spin torque oscillators (STO) provide a platform to study dissipative systems, which can be described by a non-Hermitian effective Hamiltonian. In this research project, we examine how a 2D array of STOs can be mapped to a 2D extension of the non-Hermitian SSH Model. We examine the energy spectrum by both analytical and numerical computation of the effective Hamiltonian. We examine the symmetries of the Hamiltonian and discuss how they affect the existence of edge states. Tuning the Gilbert damping or the injected spin current in the model allows us to explore the topology of the system under different parameter regimes. In this model, the edge states correspond to auto-oscillation of edge STOs while bulk oscillators do not activate. This research emphasizes the broader impacts of non-Hermitian topology in spintronic devices by exploring the possibility of real spintronic devices with non-trivial topology. With the successful completion of this research project energy dissipation in spintronic devices can be minimized; topologically protected edge states can act as a conducting channel for spin on the edges while at the same time the bulk remains non-conducting.