Pseudomorphic strain induced strong anisotropic magnetoresistance over a wide temperature range in epitaxial La0.67Ca0.33MnO3/NdGaO3(001) films

Abstract

Strong anisotropic magnetoresistance (AMR) was observed in La0.67Ca0.33MnO3 films grown coherently on the orthorhombic NdGaO3(001) substrates. With an increased orthorhombic lattice distortion due to the pseudomorphic strain, the films show not only a ferromagnetic-metal (FM) transition at TC of ∼265 K, but also the phase coexistence of FM and antiferromagnetic-insulator below ∼250 K. The phase competitions are very sensitive to the magnetic field, and more strikingly, to its orientations with respect to the crystal axes resulting in a large AMR in a broad temperature range, in addition to the conventional one peaked near TC. The films also show uniaxial magnetic anisotropy with the easy axis along the elongated b axis, suggesting that it is the strain induced spin-orbit-lattice coupling and the resultant phase competitions that control the AMR in epitaxial manganite films.