Correlation between photoluminescence and antiferromagnetic spin order in strongly correlated YMnO3 ferroelectric epitaxial thin film

The electron excitation mechanism and the spin accompanied by electron transition in a multiferroic YMnO3 epitaxial thin film were studied using photoluminescence (PL) spectroscopy. The thin film exhibits an intra-atomic transition of Mn3+ and the A1 optical coherent phonon. This study particularly focuses on the correlation between the electron transition corresponding to the on-site Coulomb energy and antiferromagnetic spin order. To clarify the complex excitation mechanism, the excitation energy and temperature dependences of the PL were analyzed. The key finding was that the intensities of the PL band at 1.43 eV increase as the excitation energy approaches the absorption peak energy corresponding to the on-site Coulomb energy and as the temperature decreases below 80 K, corresponding to the Neel temperature. These results suggest that the PL band is mediated by the spin–flip and relaxation processes.