Modification of magnetic anisotropy in Ni thin films by poling of (011) PMN-PT piezosubstrates

Abstract

This study reports the magnetic and magnetotransport properties of 20nm thick polycrystalline Ni films deposited by magnetron sputtering on unpoled piezoelectric (011) [PbMg1/3Nb2/3O3](0.68)-[PbTiO3](0.32) (PMN-PT) substrates. The magnetoresistance (MR), as well as the magnetization reversal, is found to depend on the polarization state of the piezosubstrate. Upon poling the PMN-PT substrate, which results in a transfer of strain to the Ni film, the MR value decreases by a factor of 12 at room temperature and a factor of 21 at 50K for the current direction along the PMN-PT [100] direction, and slightly increases for the current direction. Simultaneously, a strong increase in the room temperature coercive field value is observed, while the ratio between the remnant and saturation magnetization shows a pronounced minimum for the [100] direction, indicating it as a hard axis, induced by poling the piezosubstrate.