[14a-C41-7~12] 10.4 Semiconductors, organic, optical, and quantum spintronics

[14a-C41-11] Valence-band electronic structure of (Ga,Mn)As studied by high-resolution ARPES

〇Seigo Souma^1,4, Lin Chen¹, Rafal Oszwaldowski², Takafumi Sato^3,4, Fumihiro Matsukura^1,4,5,6, Tomasz Dietl^1,4,7,8, Hideo Ohio^1,4,5,6, Takashi Takahashi^1,3,4 (1.WPI-AIMR, Tohoku Univ., 2.South Dakota School M&T, 3.Dept. Phys., Tohoku Univ., 4.CSRN, Tohoku Univ., 5.CSIS, Tohoku Univ., 6.RIEC, Tohoku Univ., 7.Polish Academy of Sciences, 8.Univ. of Warsaw)

Keywords:Diluted magnetic semiconductor, photoemisssion spectroscopy

We have performed angle-resolved photoemission spectroscopy (ARPES) on high-quality (Ga,Mn)As epitaxial thin films to elucidate the electronic states responsible for the carrier-induced ferromagnetism. For (Ga,Mn)As with Curie temperature T_C of ~100 K, we observed a holelike valence band at the G point. The Fermi level E_F is located in the valence band, as evident from the clear Fermi-edge cutoff. We also observed a systematic suppression of spectral weight near E_F, likely originating from the disorder-induced soft Coulomb gap. ARPES measurements demonstrate a close relationship between T_C and the metallic spectral weight around the G point. These results strongly suggest that holes in the valence band play a key role for the ferromagnetism in (Ga,Mn)As.