Arabikhah Masomeh, Saffarzadeh Alireza
Department of Physics, Payame Noor University, PO Box 19395-3697 Tehran, Iran.
J Phys Condens Matter. 2019 Nov 6;31(44):445001. doi: 10.1088/1361-648X/ab31f4. Epub 2019 Aug 5.
We explore the scattering of Dirac electrons in a double-gated topological insulator in the presence of magnetic proximity effects and warped surface states. It is found that a magnetic field can shift the Dirac cone in momentum space and deform the constant-energy contour, or opens up a band gap at the Dirac point, depending on the magnetization orientation. The double gate voltage induces quantum wells and/or quantum barriers on the surface of topological insulators, generating surface resonant tunnelling states. It is found that the hexagonal warping effect can increase the electronic transport at high energies when the constant-energy contour exhibits a snowflake shape. The energy-dependent conductances in the parallel and antiparallel magnetic configurations exhibit out-of-phase oscillations due to the quantum interference of propagating waves in the region between the two magnetized segments. Although the conductance spectrum of the double-well structure is higher than that of the double-barrier structure, the magnetoresistance ratio versus the separation distance between the two magnetized barriers exhibits pronounced oscillations due to the resonant tunnelling states. We show that the surface state transport can be controlled by the exchange field and gate voltage without breaking time reversal symmetry, suggesting that the double gated and magnetized topological insulators can be utilized to achieve a large magnetoresistance ratio with a tunable sign.
我们研究了在存在磁近邻效应和翘曲表面态的双栅拓扑绝缘体中狄拉克电子的散射。研究发现，磁场可在动量空间中移动狄拉克锥并使等能轮廓变形，或者根据磁化方向在狄拉克点处打开带隙。双栅电压在拓扑绝缘体表面诱导出量子阱和/或量子势垒，产生表面共振隧穿态。研究发现，当等能轮廓呈现雪花形状时，六边形翘曲效应可在高能下增加电子输运。由于在两个磁化段之间区域中传播波的量子干涉，平行和反平行磁配置下的能量相关电导呈现异相振荡。尽管双阱结构的电导谱高于双势垒结构，但由于共振隧穿态，磁阻比相对于两个磁化势垒之间的分离距离呈现明显振荡。我们表明，表面态输运可通过交换场和栅电压进行控制而不破坏时间反演对称性，这表明双栅和磁化的拓扑绝缘体可用于实现具有可调符号的大磁阻比。
