Nonlinear magnetic vortex dynamics in a circular nanodot excited by spin-polarized current
1 Depto. Física de Materiales, Facultad de Química, Universidad del País Vasco, UPV/EHU, San Sebastián 20018, Spain
2 IKERBASQUE, Basque Foundation for Science, Bilbao 48011, Spain
3 General Numerics Research Laboratory, Jena 07745, Germany
Nanoscale Research Letters 2014, 9:386 doi:10.1186/1556-276X-9-386Published: 8 August 2014
We investigate analytically and numerically nonlinear vortex spin torque oscillator dynamics in a circular magnetic nanodot induced by a spin-polarized current perpendicular to the dot plane. We use a generalized nonlinear Thiele equation including spin-torque term by Slonczewski for describing the nanosize vortex core transient and steady orbit motions and analyze nonlinear contributions to all forces in this equation. Blue shift of the nano-oscillator frequency increasing the current is explained by a combination of the exchange, magnetostatic, and Zeeman energy contributions to the frequency nonlinear coefficient. Applicability and limitations of the standard nonlinear nano-oscillator model are discussed.