Control of orbital ordered state in strained Nd0.25Sr1.75MnO4 films

Epitaxial strain effect has been studied for Nd0.25Sr1.75MnO4 thin films on (100) surfaces of two different isostructural (single-layered perovskite) substrates, LaSrAlO4 and LaSrGaO4. Due to the anisotropic strain in the MnO2 plane, the orientation-controlled films were stabilized with the structure consistent with that of C-type antiferromagnetic and d(3x)2(-r)2 ferro-orbital-ordered state. Measurements of highly anisotropic optical spectra show that the tensile strain in the MnO2 plane aligns ferroically the direction of d(3x)2(-r)2 orbitals parallel to the film plane, whereas compressive strain does those vertical to the film plane. These results indicate that the direction of the ferroic ordering of d(3x)2(-r)2 orbitals can be controlled by external uniaxial pressure, implying a potential for a switching device. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3427428]