Epitaxial-Strain Effects on Electronic Structure and Magnetic Properties of Hexagonal YMnO3 Thin Films Studied by Femtosecond Spectroscopy

Abstract

In this paper, (001)-oriented hexagonal YMnO3 (h-YMO) thin films with various nominal strain states were deposited on MgO(100), MgO(111), and YSZ(111) substrates by pulsed laser deposition. The in-plane orientation alignment and substrate-induced epitaxial strain between the h-YMO films and substrates are examined by X-ray diffraction (XRD) theta-2 theta, I broken vertical bar, and omega scans. The effects of epitaxial strain on the on-site Mn d-d transition energy E (dd) (T), and the N,el temperature (T (N)) in these thin films are investigated by wavelength-tunable ultrafast pump-probe techniques. We find that the changes of E (dd) (T) and T (N) depend on the type and magnitude of the epitaxial strain. The possible mechanisms for the observed strain effect on the electronic structure and associated magnetism are discussed.