利用第一原理計算模擬研究在巨大Rashba半導體溴碲化鉍上的準粒子干涉

First-Principle-Calculations and Simulations of Quasiparticle Interference at the Surface of a Giant Rashba Semiconductor BiTeBr

楊博亞(Po-Ya Yang)

指導教授 ： 林敏聰

共同指導教授 ： 魏金明(Ching-Ming Wei)

國立臺灣大學/理學院/物理學研究所/碩士(2016年)

https://doi.org/10.6342/NTU201601347

摘要

碲鉍⻧化物 (bismuth tellurohalides) 是擁有巨大 Rashba 效應的半導體,存在於 其帶有相反極性的兩端面中,帶有的自旋-動量垂直關係 (spin-momentum locked) 的載子,有應用在自旋電子學裝置的潛力。我們使用密度泛函方法,研究溴碲化 鉍的碲端面的晶格結構、表面電子組態。並且,藉由討論在倒空間等能量電子 組態分佈 (constant energy contours) 所有可能的態轉換,我們模擬出準粒子干涉 (quasiparticle interference) 條紋。結合狀態密度 (joint density of states) 和自旋散 射機率 (spin scattering probability) 分別是沒有考慮、有考慮自旋版本的準粒子干 涉。最後,比較模擬和實驗的準粒子干涉條紋,發現自旋不守恆的反向散射,不 存在於溴碲化鉍的碲端面上。

關鍵字

Rashba 效應 ； 溴碲化鉍 ； 掃描式穿隧電子顯微鏡 ； 掃描式穿隧電子能譜 ； 密度泛函理論 ； 準粒子干涉

並列摘要

Bismuth Tellurohalides are semiconductors with a giant Rashba e ect. They have two oppositely polarised surfaces with two-dimensional spin-momentum locked he- lical charge carriers, which are good candidates to achieve the goal of spin control in novel spintronic devices. Within the framework of density functional theory, we study the band structure of the Te-termination of ordered phase bismuth telluro- bromide, BiTeBr. Considering all the possible parings of initial and nal states in the constant energy contours (CEC), we further simulate the quasiparticle interfer- ence (QPI) patterns. By excluding or including the helical spin texture, there are actually two versions of simulated QPI patterns, joint density of states (JDOS) and spin scattering probability (SSP). Finally, we compare the simulated phenomena with measured tunnelling spectro-microscopy maps. We show that backscattering with opposite spin is absent in this system.

並列關鍵字

Rashba effect ； BiTeBr ； scanning tunnelling microscopy ； scanning tunnelling spectroscopy ； density functional theory ； quasi-particle interference

參考文獻

[2] Xiao-Liang Qi and Shou-Cheng Zhang. Topological insulators and supercon- ductors. Reviews of Modern Physics, 83(4):1057–1110, October 2011.

[46] Cheng-Rong Hsing, Ching Cheng, Jyh-Pin Chou, Chun-Ming Chang, and Ching-Ming Wei. Van der Waals interaction in a boron nitride bilayer. New Journal of Physics, 16(11):113015, November 2014.

[1] A. Manchon, H. C. Koo, J. Nitta, S. M. Frolov, and R. A. Duine. New perspec- tives for Rashba spin-orbit coupling. Nature Materials, 14(9):871–882, Septem- ber 2015.

[5] S. V. Eremeev, I. A. Nechaev, Yu. M. Koroteev, P. M. Echenique, and E. V. Chulkov. Ideal Two-Dimensional Electron Systems with a Giant Rashba-Type Spin Splitting in Real Materials: Surfaces of Bismuth Tellurohalides. Physical Review Letters, 108(24):246802, June 2012.

[6] J. E. Ho man, K. McElroy, D.-H. Lee, K. M. Lang, H. Eisaki, S. Uchida, and J. C. Davis. Imaging Quasiparticle Interference in Bi2Sr2CaCu2O8+δ. Science, 297(5584):1148–1151, August 2002.