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Photo-induced spin dynamics in ferromagnetic semiconductor $p$-(Ga,Mn)As

Y. Mitsumori·A. Oiwa·T. Slupinski·H. Maruki·Y. Kashimura·F. Minami·H. Munekata
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Abstract

Spin dynamics in ferromagnetic $p$-(Ga,Mn)As ($x$ = 0.011, $T_{C}$ = 30 K) has been studied by carefully comparing the decay time of the photo-induced reflectivity change with the transient behavior of polar Kerr rotation induced by photo-generated carrier spins with a femtosecond light pulse of various polarizations. As to the rising process, the rate of Kerr rotation is found comparable to the generation rate of spin-polarized carriers. For the decay process, the Kerr rotation and reflectivity signal both show the same decay rate at above the $T_{C}$, whereas, below the $T_{C}$, the former becomes slower than the latter. The magnitude of Kerr rotation suggests that 10$^{2}$ Mn spins are revolved by injecting one hole spin. On the basis of these observations, collective rotation of ferromagnetically coupled Mn spins is discussed in terms of $p$-$d$ exchange interaction and successive transverse spin relaxation. Development of another long-lived behavior under external perpendicular magnetic fields is also disclosed.

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Y. Mitsumori, A. Oiwa, T. Slupinski, H. Maruki, Y. Kashimura, F. Minami, H. Munekata. 2003-07-11. Photo-induced spin dynamics in ferromagnetic semiconductor $p$-(Ga,Mn)As. https://arxiv.org/abs/cond-mat/0307268

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