摘要
Ultrafast quasiparticle dynamics of single crystalline LaOFeAs were investigated by pump-probe measurement.The compound experiences structural and spin-density-wave(SDW)phase transitions at 150 K(TS1)and 130 K(TS2),respectively.The relaxation time of quasiparticles was somewhat temperature independent at high temperature but exhibited a sharp upturn at TS1and reached the maximum at approximately TS2.The remarkable slowing down of quasiparticle relaxation time is caused by the formation of energy gap.By employing the Rothwarf-Taylor model analysis,we found that there should be already energy gaps opening just below the structural transition.The magnitude of SDW gap was identified to be 72 meV.
Ultrafast quasiparticle dynamics of single crystalline LaOFeAs were investigated by pump-probe measurement. The compound experiences structural and spin-density-wave （SDW） phase transitions at 150 K （TS1 and 130 K （TS2）, respectively. The relax- ation time of quasiparticles was somewhat temperature independent at high temperature but exhibited a sharp upturn at TS1 and reached the maximum at approximately TS2. The remarkable slowing down of quasiparticle relaxation time is caused by the formation of energy gap. By employing the Rothwarf-Taylor model analysis, we found that there should be already energy gaps opening just below the structural transition. The magnitude of SDW gap was identified to be 72 meV.
基金
supported by the National Science Foundation of China(Grant No.2011CB921701)
the National Basic Research Program of China(Grant No.2012CB821403)
