Measurements of Thermally Activated Hopping of the Magnetization Over a Barrier in a Mesoscale Permalloy System*

Square, permalloy dots with sides 200-250nm and a thickness of 10nm have proven to be a model system for exploring random telegraph noise (RTN)¹. One property not explored in these previous studies is the RTN attempt frequency that is expected to follow an Arrhenius Law. We have explored the RTN attempt frequency in similarly sized permalloy dots as a function of temperature and barrier height controlled by an external magnetic field. Using the Arrhenius Law to analyze the RTN attempt frequency, both the characteristic attempt frequency and barrier height were determined as functions of applied magnetic field and temperature.
1. Endean, Daniel E., et al. "Tunable random telegraph noise in individual square permalloy dots." Applied Physics Letters 104.25 (2014): 252408.