[21a-131-1~11] 10.4 半導体スピントロニクス・超伝導・強相関

▼ [21a-131-9] Observation of impurity band related transitions in high Curie temperature p-type ferromagnetic semiconductor (Ga,Fe)Sb

〇(M2)Sriharsha Karumuri¹、Anh Le Duc^1,2、Tu Nguyen Thanh¹、Masaaki Tanaka^1,3 (1.EEIS, Univ. of Tokyo、2.IEI, Univ. of Tokyo、3.CSRN, Univ. of Tokyo)

キーワード：(Ga,Fe)Sb, Impurity Band, Magnetic Circular Dichroism (MCD)

(Ga,Fe)Sb is a ferromagnetic semiconductor with high Curie temperature (T_C) which is promising for the future of spintronics. In this study we investigate the band structure and the position of the Fermi Level using infrared magnetic circular dichrosim (MCD) spectroscopy (photon energy E_ph = 0.6 - 1.8 eV ) of a series of (Ga_1-x,Fe_x)Sb samples with the Fe concentrations x = 0%, 2%, 6%, 10%, 20%. From the MCD spectra we observed two peaks, one positive peak E_a close to intrinsic band gap of GaSb (~0.8 eV), and a new negative peak E_b around 1.4 eV. As x increases the position of the E_a red-shifted from ~0.8 to ~0.54 eV, while that of E_b blue-shifted from ~1.4 to ~1.57 eV. We show these two peaks and their dependence on x could be explained by the presence of an impurity band in the band gap with the Fermi level lying inside it. This could be useful in understanding the origin of high T_C and also in device applications.