Origin of robust nanoscale ferromagnetism in Fe-doped Ge revealed by angle-resolved photoemission spectroscopy and first-principles calculation
角度分解光電子分光および第一原理計算による鉄をドープしたゲルマニウムにおけるナノスケールの強磁性の起源の研究
坂本 祥哉*; 若林 勇希*; 竹田 幸治
; 藤森 伸一
; 鈴木 博人*; 伴 芳祐*; 山上 浩志; 田中 雅明*; 大矢 忍*; 藤森 淳*
Sakamoto, Shoya*; Wakabayashi, Yuki*; Takeda, Yukiharu; Fujimori, Shinichi; Suzuki, Hakuto*; Ban, Yoshisuke*; Yamagami, Hiroshi; Tanaka, Masaaki*; Oya, Shinobu*; Fujimori, Atsushi*
Ge
Fe
(Ge:Fe) shows ferromagnetic behavior up to a relatively high temperature of 210 K and hence is a promising material for spintronic applications compatible with Si technology. We have studied its underlying electronic structure by soft X-ray angle-resolved photoemission spectroscopy measurements and first-principles supercell calculation. We observed finite Fe 3
components in the states at the Fermi level (
) in a wide region of momentum space, and the
was located
0.35 eV above the valence-band maximum of the host Ge. Our calculation indicates that the
is also within the deep acceptor-level impurity band induced by the strong
-
(
) hybridization. We conclude that the additional minority-spin
electron characteristic of the Fe
state is responsible for the short-range ferromagnetic coupling between Fe atoms.