Tuning the ground state of La0.67Ca0.33MnO3 films via coherent growth on orthorhombic NdGaO3 substrates with different orientations

The commensurate La0.67Ca0.33MnO3 films, of which the bulk is a ferromagnetic-metal (FM), can show strikingly different ground states when grown on NdGaO3 substrates of various orientations. With a larger orthorhombic lattice distortion in the substrates, the (110) films can grow essentially strain-free, but the (100) and (001) films are anisotropically strained, accompanied by an increased orthorhombicity. As a result, while the (110) films show constantly a bulklike FM ground state, the others behave dramatically different, i.e., they show a tunable antiferromagnetic-insulator (AFI) phase below similar to 250 K with strong phase instability in the wide temperature range and at low magnetic fields. Considering that in La1-xCaxMnO3 system the AFI phase is highly involved with the orthorhombic lattice distortion, the different ground state in (100) and (001) films could be ascribed to the epitaxial anisotropic strain, which enhances the orthorhombicity of the films via increasing the rotation and deformation of the MnO6 octahedra.