Angle-resolved photoemission analysis of electronic structures for thermoelectric properties of off-stoichiometric Fe
V
Al alloys
非化学量論組成Fe
V
Alの角度分解光電子分光による電子状態解析
曽田 一雄*; 原田 翔太*; 林 利光*; 加藤 政彦*; 石川 文洋*; 山田 裕*; 藤森 伸一
; 斎藤 祐児

Soda, Kazuo*; Harada, Shota*; Hayashi, Toshimitsu*; Kato, Masahiko*; Ishikawa, Fumihiro*; Yamada, Yu*; Fujimori, Shinichi; Saito, Yuji
The electronic states of Heusler(L21)-type off-stoichiometric Fe
V
Al have been investigated by soft X-ray angle-resolved photoelectron spectroscopy (ARPES) in order to clarify the origin of their large thermoelectric powers, which cannot be explained in terms of the rigid band model. In off-normal and normal ARPES, Fe
V
Al shows a weakly dispersive bulk band around the binding energy of 0.3 eV in the
-X direction and an almost dispersion-less one around 0.3 eV in a gap of dispersive bulk bands in the
-L direction, which is attributed to the anti-site Fe defect. At the
point, the bulk band does not appear to cross the Fermi level
, consistent with the rigid band model for the excess Fe content bringing about the increase in the valence electrons, but no band crossing
down is found at the X point. The anti-site Fe defect states near
might push up the band at the X point and cause the p-type thermoelectric properties, unexpected with the rigid band picture. The change in the electronic structures and thermoelectric properties are discussed on the off-stoichiometry and substitution of the forth element.