Sign reversal of anisotropic magnetoresistance in La0.7Ca0.3MnO3/SrTiO3 ultrathin films

摘要

We present the observation of strain induced sign reversal of anisotropic magnetoresistance (AMR) in LaCaMnO (LCMO) ultrathin films (thickness ∼ 4 nm) deposited on SrTiO (001) substrate (STO). We have also observed unusually large AMR (∼24%) in LCMO/STO thin films with thickness of 6 nm below but close to its Curie temperature (T) which decreases as the film thickness increases. The sign reversal of AMR (with a maximum value of −6%) with magnetic field or temperature for the 4 nm thin film may be attributed to the increase in tensile strain in the plane of the thin film which in turn facilitates the rotation of the magnetization easy axis.