[18p-PB1-1~73] 10 Spintronics and Magnetics (Poster)

▼ [18p-PB1-2] Observation of quantum size effect at the conduction band bottom of n-type ferromagnetic semiconductor (In,Fe)As thin films

〇(B)Shingo Kaneta¹, Anh Le Duc^1,2, Masaaki Tanaka^1,3 (1.Univ. of Tokyo, 2.IEI, Univ. of Tokyo, 3.CSRN, Univ. of Tokyo)

Keywords:ferromagnetic semiconductor, quantum size effect, magnetic circular dichroism

N-type III-V ferromagnetic semiconductor (In,Fe)As is promising due to its unique properties such as the large s-d exchange interaction energy, large spontaneous spin splitting in the conduction band (CB), and high coherency of electron carriers. In (In,Fe)As ultrathin films, previous works have revealed the quantum size effect (QSE) at the L and X points, but its effect on the CB bottom (Γ point) is unknown. Here, by performing infra-red magnetic circular dichroism (MCD) spectroscopy on a series of samples consisting of Be-doped (In_0.92,Fe_0.08)As (t = 8 - 14 nm) / AlSb buffer grown on GaAs (001) substrates, we observed oscillatory behavior in the MCD spectra, whose peak positions systematically blue-shift with decreasing t. The peak positions can be fitted well by the theoretical values of the 2nd, 3rd and 4th quantized levels in rectangular QW potentials with infinite potential barriers. These results show the evidence of the QSE in the CB bottom of (In,Fe)As, which is essential for quantum transport applications of this material.