Dynamical measurement of domain-wall nucleation and annihilation in individual amorphous Co particles

Abstract

We present magnetization measurements of individual amorphous Co particles (300 nm×200 nm×30 nm) patterned by electron-beam lithography. The hysteresis loops show mainly two magnetization jumps corresponding to domain-wall nucleation and annihilation. The angular dependence of these magnetization jumps is measured and the temperature dependence (0.1–6 K) of the nucleation and the annihilation processes is investigated by two independent methods: switching field and switching time measurements. Finally we compare the results obtained on one particle with those of an array of about 2×${10}^7$ particles. We show experimentally that the dynamical properties measured on individual particles are connected with an unusual 1/T relaxation of the array of particles. © 1996 The American Physical Society.