Raman spectroscopy of the Jahn–Teller phonons in a magnetic LaMnO3 thin film grown on KTaO3.

Bulk LaMnO₃ is an A-type antiferromagnetic material in which the Jahn–Teller (JT) planes each have a ferromagnetic arrangement, but are stacked in antiparallel. Here, we report the growth of epitaxial LaMnO₃ films on (001)-oriented cubic KTaO₃ substrates in such a way that the JT plane is parallel to the nonmagnetic substrate. We verify the presence of the JT distortion and confirm the orientation of the plane by symmetry analysis with angle-resolved polarized Raman spectroscopy. The temperature evolution of the Raman spectra indicates that the B_1g JT phonon softens below the magnetic transition temperature of ∼145 K, where ferro- or ferri-magnetism with magnetic easy axis along the out-of-plane direction is exhibited. [ABSTRACT FROM AUTHOR]