Studies of the magnetoelastic inverse Wiedemann effect in pulsed laser depositedcylindrical cobalt films

Abstract

Cylindrical soft magnetic Co films, nanostructured with a grain size of 1–2 nm and between and 90 nm in thickness, were produced by the pulsed laser deposition technique. Thesefilms showed a magnetostrictive property. The magnetoelastic inverse Wiedemann effect, orIWE, of longitudinal magnetization as a function of the circular applied magnetic field,Mz–Hϕ, was measured. The IWE made it possible to explain the magnetization processesaccording to an initial reversible rotation of the magnetization followed by magneticwall nucleation and propagation. A magnetization rotation model allowed us tocompare the reversible part and the first irreversible magnetization processescorresponding to the IWE. In this way, the values of the helical magnetic anisotropy,Kh, due to thehelical stresses, σh, generated by an applied torque to the films, were determined.A linear increase of the nucleating magnetic wall field,HN, with the appliedtorque, or with σh, was observed. In addition, the IWE made it possible to establishthe non-dependence of the saturation magnetostriction constant,λs, on the sample thickness and to determine the value of this negative isotropic .