  Electron spin dynamics in intrinsic bulk Indium Phosphide (InP) semiconductor
is studied by time resolved pump probe reflectivity (TRPPR) technique using the
co- and counter-circularly polarized femtosecond pulses at room temperature and
70 K. The reflectivity change from bleaching into absorption is observed with
increasing pump photon energy, which can be explained in terms of the spin
sensitive band filling and band gap renormalization effects. Density dependence
of electron spin relaxation time shows similar tendency at room temperature and
70 K. With increasing carrier density, the electron spin relaxation time
increases and then decreases after reaching a maximum value. Our experimental
results agree well with the recent theoretical prediction [Jiang and Wu, Phys.
Rev. B 79, 125206 (2009)] and D'yakonov-Perel' mechanism is considered as a
dominating contribution to the electron spin relaxation in intrinsic bulk InP
semiconductor.
