Ultrafast spectroscopy of the Mn3+ dd transition in YMnO3 film

Abstract

Photoinduced carrier dynamic behavior of the Mn3+ 3d resonance excitation of YMnO3 thin film is studied by the femtosecond time resolved spectroscopy. The photon energy of the pump pulse is tuned to 1.70 eV, which is corresponding to the Mn3+ 3d energy level at room temperature. With resonant excitation, the transient transmission signals at the zero-delay time gradually increase with temperature increasing. The temperature dependent transmission change results from the blue shift of the Mn3+ 3d energy level, which is believed to originate from the short-range antiferromagnetic order in YMnO3 film. In addition, the fast and slow relaxations of the transient signal arise from electronic-phonon and phonon-spin interactions, respectively. When the temperature is lower than TN, the relaxation time of the fast process increases significantly, which indicates that the strength of electronic-phonon coupling is restrained by the long-range antiferromagnetic order.