Optical and magnetic properties of CuMnO2 epitaxial thin films with a delafossite-derivative structure

Abstract

A distorted delafossite CuMnO2, called crednerite, was formed into epitaxial thin films on MgAl2O4 (111) substrates by pulsed laser deposition method. X-ray diffraction revealed that the films had high crystalline quality with epitaxial relationship of CuMnO2 (001)//MgAl2O4 (111) and CuMnO2 [100]//MgAl2O4 ⟨11-2⟩. The ultraviolet-visible optical response revealed a distinct absorption peak at 4.5 eV presumably with excitonic nature and broad peaks at 3.0 and 3.7 eV assignable to O 2p–Mn 3d charge transfer excitation. Small magnetic hysteresis with remanent magnetization of 0.04μB/Mn was observed below 20 K, representing canted antiferromagnetic spin ordering.