[8a-Z08-1~8] 10.4 半導体スピントロニクス・超伝導・強相関

▼ [8a-Z08-1] Transport and magnetic properties of quaternary-alloy ferromagnetic semiconductor (In,Ga,Fe)Sb

〇Tomoki Hotta¹、Kengo Takase¹、Kosuke Takiguchi¹、Suriharsha Karumuri¹、Anh Le Duc^1,2,3、Masaaki Tanaka^1,4 (1.Univ. of Tokyo、2.IEI, Univ. of Tokyo、3.PRESTO, JST、4.CSRN)

キーワード：ferromagnetic semiconductor, spintronics

Ferromagnetic semiconductors (FMSs) are promising materials for spintronics applications because they are compatible with the highly established semiconductor technology. Recently we have successfully grown a quaternary-alloy FMS (In_1-x-y,Ga_x,Fe_y)Sb with the Fe concentration y = 16%. This new FMS is promising to achieve good controllability of material properties, including lattice constant, band structure, carrier type and magnetic anisotropy. In this work, we investigate in detail the transport and magnetic properties of Fe-doped quaternary-alloy FMS (In_1-x-y,Ga_x,Fe_y)Sb thin films with different Fe concentration y and Ga concentration x. The sample structure under study consists of (from top to bottom) InSb (2 nm) / (In_1-x-y,Ga_x,Fe_y)Sb (15 nm) / AlSb (100 nm) / AlAs (6 nm) / GaAs (100 nm) on a semi-insulating GaAs(001) substrate, grown by low temperature molecular beam epitaxy (LT-MBE). A scanning transmission electron microscopy (STEM) lattice image of the 15 nm thick (In_0.74,Ga_0.1,Fe_0.16)Sb layer shows that the crystal structure is of zinc-blende type without any visible second phase. Normalized magnetic circular dichroism (MCD) spectra of the same film measured at 5 K with magnetic fields of 1 T, 0.5 T and 0.2 T applied perpendicularly to the film plane overlap on a single curve in the whole photon energy range from 1.5 eV to 4.5 eV, indicating intrinsic and homogeneous ferromagnetism. In (In_0.84-x,Ga_x,Fe_0.16)Sb samples (x = 2, 6, 8, 10%), the carrier type can be changed between p-type and n-type by changing x while a high T_C > 300 K is maintained.