Research Paper 3次元電子正孔系におけるポリ励起子相出現可能性の理論的解明

前園, 涼

拡散モンテカルロ法を用い電子正孔ガスの相図を解明した。「実効相互作用+励起子複合体のみの波動関数」と記述し、「電子正孔質量比(量子ダイナミクス効果)」と「実効相互作用の遮蔽パラメタ(電子相関効果)」の2パラメタ空間で相図を構成し「ドナー不純物に束縛される励起子の安定化程度」に基本的な情報を提供した。電子ガス模型での展開と並行し、層状カルコゲナイドなど遷移金属化合物系層状物質の解析にも研究展開し、具体的なバンド構造から有効質量模型に持ち込む過程で非自明な不安定格子振動モードを発見するなどの成果を得た。:Phase diagrams of electron-hole systems are investigated by using diffusion Monte Carlo method. The system is modelled by the effective inter-particle interactions with tunable parameters for the Coulombic screenings and the mass ratio between electrons and holes. A phase diagram is evaluated as a function of the screening strength (representing electronic correlation effect) and the mass ratio (quantum dynamics of nuclei). It may describe how much stable when an exciton is bound by a donor impurity in semiconductors. As well as the work on electron-hole models, we worked on real materials, such as layered pnictides, to estimate realistic parameters for the ratio and screening effects. On the investigations, we found the lattice instability through its phonon properties and made an successful explanation of the experimental facts under intensive debates about the origin of the instability.

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