The effect of interfaces on magnetic activation volumes in single crystal Co 2FeSi Heusler alloy thin films

Abstract

Structural and magnetization reversal studies have been carried out on single crystal Co 2FeSi thin films grown on MgO (001) substrates. The films are highly L2 1 ordered after annealing above 500 °C. Magnetization reversal has been investigated by measurements of the activation volumes (V act) within the films. This volume represents the unit of reversal in a magnetic material. V act (∼4 × 10 3 nm 3) has been found to be independent of the physical structure. V act is found to correspond to an array of periodic misfit dislocations at the Co 2FeSi/MgO interface. Such a small V act potentially prevents coherent magnetization reversal as required for giant magnetoresistance or tunnel magnetoresistance devices. © 2012 American Institute of Physics.