||Sudden restoration of the band ordering associated with the ferromagnetic phase transition in a semiconductor
Muneta, Iriya ,
Ohya, Shinobu ,
Terada, HiroshiTanaka, Masaaki
72016-06-28 , Nature Publishing Group , Department of Electrical Engineering and Information Systems, The University of Tokyo , Center for Spintronics Research Network, Graduate School of Engineering, The University of Tokyo
UTokyo Research掲載「半導体の基礎物理学で新たな発見」 URI: http://www.u-tokyo.ac.jp/ja/utokyo-research/research-news/new-discovery-in-semiconductor-physics.html
UTokyo Research "New discovery in semiconductor physics" URI: http://www.u-tokyo.ac.jp/en/utokyo-research/research-news/new-discovery-in-semiconductor-physics.html
The band ordering of semiconductors is an important factor in determining the mobility and coherence of the wave function of carriers, and is thus a key factor in device performance. However, in heavily doped semiconductors, the impurities substantially disturb the band ordering, leading to significant degradation in performance. Here, we present the unexpected finding that the band ordering is suddenly restored in Mn-doped GaAs ((Ga,Mn)As) when the Mn concentration slightly exceeds B0.7% despite the extremely high doping concentration; this phenomenon is very difficult to predict from the general behaviour of doped semiconductors. This phenomenon occurs with a ferromagnetic phase transition, which is considered to have a crucial role in generating a well-ordered band structure. Our findings offer possibilities for ultra-high-speed quantum-effect spin devices based on semiconductors.