Thermal fluctuation effects on quasistatic magnetic switching of patterned Ni81Fe19 elements (invited)

We have studied quasistatic magnetic switching of electron-beam patterned Ni81Fe19 (NiFe) elements over a wide range of temperatures. Switching properties depend on both lateral and thickness dimensions of the patterned structures. In large aspect-ratio elements, the switching between the two bistable states occurs through thermally activated nucleation and the switching field depends linearly on temperature. As the aspect ratio decreases, a third stable remanent state-trapped vortex state develops, but the switching fields between different states also linearly depend on temperature. As the film thickness decreases, the trapped vortex population clearly becomes thermally activated.