Study of Multiferroic Phase Transtion of TbMn2O5 with Two Colors Ultrafast Pump-Probe Measurement

• Main Authors: Hsu, Kuo-Chien, 徐國謙
• Other Authors: Chi, Cheng-Chung
• Format: Others
• Language: en_US
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/84212515303958429202

博士 === 國立清華大學 === 物理學系 === 99 === We use two colors (400nm pump and 800nm probe) ultrafast pump-probe technique to study multiferroic phase transition of TbMn2O5 single crystal. The reflectivity of the probe beam alone we measured for the laser polarization parallel to the crystalline b and c axes respectively are about Rb=21.3 % and Rc=22.5 %. The rapid rise of the transient reflectivity is comparable to the pulse duration. Following the initial signal rise, only the “probe b” signals showed a fast signal drop to a plateau within several picoseconds. The fast relaxation rates of (pump c, probe b), (pump b, probe b) and the plateau level (pump b, probe c) correlate well with the temperature dependence of the spontaneous of electric polarization along b-axis of TbMn2O5. Furthermore, the temperature dependence of the plateau of (pump c, probe c) correlates with the onset of the anti-ferromagnetic transition of our sample. The temperature dependence for (pump c, probe b) and (pump b, probe b) are relatively weak but they seem to correlate with the onset of the lower incommensurate anti-ferromagnetic transition.