Influence of elastically pinned magnetic domain walls on magnetization reversal in multiferroic heterostructures

In elastically coupled multiferroic heterostructures that exhibit full domain correlations between ferroelectric and ferromagnetic sub-systems, magnetic domain walls are firmly pinned on top of ferroelectric domain boundaries. In this work we investigate the influence of pinned magnetic domain walls on the magnetization reversal process in a Co40Fe40B20 wedge film that is coupled to a ferroelectric BaTiO3 substrate via interface strain transfer. We show that the magnetic field direction can be used to select between two distinct magnetization reversal mechanisms, namely (1) double switching events involving alternate stripe domains at a time or (2) synchronized switching of all domains. Furthermore, scaling of the switching fields with domain width and film thickness is also found to depend on field orientation. These results are explained by considering the dissimilar energies of the two types of pinned magnetic domain walls that are formed in the system.

Piezoelectric strain induced variation of the magnetic anisotropy in a high Curie temperature (Ga,Mn)As sample

We show that effective electrical control of the magnetic properties in the ferromagnetic semiconductor (Ga,Mn)As is possible using the strain induced by a piezoelectric actuator even in the limit of high doping levels and high Curie temperatures, where direct electric gating is not possible. We demonstrate very large and reversible rotations of the magnetic easy axis. We compare the results obtained from magneto-transport and SQUID magnetometry measurements, extracting the dependence of the piezo-induced uniaxial magnetic anisotropy constant upon strain in both cases and detailing the limitations encountered in the latter approach.