絕緣體/拓樸絕緣體超晶格的超導相之研究

Superconducting Phases in a Superlattice composed of Normal and Topological Insulators

吳健弘(Jian-Hong Wu)

指導教授 ： 牟中瑜

國立清華大學/理學院/物理學系/碩士(2020年)

摘要

在本文中，我們考慮了一個由絕緣體和拓撲絕緣體組成的超晶格，並分析了在該複合系統中可能形成的超導狀態。為了考慮電子配對，我們同時考慮了超晶格表面態之間的庫侖交互作用和電子 -聲子交互作用。庫侖勢能是通過近似求解超晶格的格林函數獲得的，而電子-聲子交互作用則通過考慮聲子來獲得。平均場理論藉由通過考慮最近鄰界面之間的交互作用來構建。於是我們獲得了間隙方程，並討論了在不同厚度範圍內不同交互作用強度的相圖。結果表明，在一定的交互作用強度下，三重態對占主導地位，此時的系統是拓撲超導體。

關鍵字

超導 ； 超晶格 ； 絕緣體 ； 拓樸絕緣體

並列摘要

In this thesis, we consider a superlattice composed of normal and topological insulators and analyze the superconducting states that can form in this composite system. To consider the electron pairing, we include both the Coulomb interaction and the electron-phonon interaction between interface states in the superlattice. The Coulomb potential energy is obtained by solving the Green’s function for the superlattice approximately, while the electron-phonon interaction is included by considering the acoustic phonons. A mean field theory is constructed by considering interactions between nearest-neighbouring interfaces. We obtain the gap equations and discuss the phase diagram for different interaction strengths at different regimes of thickness. It is shown that at certain interaction strength, the triplet pairing dominates and the system is a topological superconductor.

並列關鍵字

superconductivity ； superlattice ； normal insulator ； topological insulator

參考文獻

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