Temperature Dependence of Domain Wall Creep in Thin Ni-Fe Magnetic Film

Abstract

This paper presents the results of an experimental program undertaken to determine the temperature dependence of the creep of magnetic domain walls in a uniaxial thin Ni-Fe magnetic film and its relationship to the temperature dependence of the anisotropy field (Hk), the coercive force (Hc), and the critical fields required to initiate domain wall motion. The temperature dependence of creep velocity is measured with a peak transverse ac magnetic field (HT ac) applied in the hard direction of magnetization and a dc longitudinal field (HL) applied in the easy direction. Measurements were made on a vacuum deposited thin film, 1613 Å thick with a composition of 82.2% Ni and 17.8% Fe, using the longitudinal Kerr magneto-optic effect. The thin film temperature was maintained to within ±0.8°C over the range 8.9 to 81.7°C. Experimental results show that domain wall creep velocity and the magnetic properties of the film are temperature dependent and that the temperature dependence of the former is related by a transformation to the temperature dependence of the latter. Curves of creep velocity, Hc, Hk as functions of temperature are given, and experimental and constructed curves of constant creep velocity were plotted at several temperature values to show that a correlation exists between the experimentally measured values and the calculated values.