Optical spectroscopic investigation on the coupling of electronic and magnetic structure in multiferroic hexagonal RMnO3 (R = Gd, Tb, Dy, and Ho) thin films

摘要

We investigated the effects of temperature and magnetic field on theelectronic structure of hexagonal RMnO3 (R = Gd, Tb, Dy, and Ho) thin filmsusing optical spectroscopy. As the magnetic ordering of the system wasdisturbed, a systematic change in the electronic structure was commonlyidentified in this series. The optical absorption peak near 1.7 eV showed anunexpectedly large shift of more than 150 meV from 300 K to 15 K, accompaniedby an anomaly of the shift at the Neel temperature. The magnetic fielddependent measurement clearly revealed a sizable shift of the correspondingpeak when a high magnetic field was applied. Our findings indicated strongcoupling between the magnetic ordering and the electronic structure in themultiferroic hexagonal RMnO3 compounds.