Electrically Tunable Wafer-Sized Three-Dimensional Topological Insulator Thin Films Grown by Magnetron Sputtering

Three-dimensional(3 D) topological insulators(TIs) are candidate materials for various electronic and spintronic devices due to their strong spin-orbit coupling and unique surface electronic structure.Rapid,low-cost preparation of large-area TI thin films compatible with conventional semiconductor technology is the key to the practical applications of TIs.Here we show that wafer-sized Bi₂ Te₃ family TI and magnetic TI films with decent quality and well-controlled compositio...     

Gap Opening Mechanism at the Dirac Point in the Electronic Spectrum of Gd-Doped Topological Insulator

Physics of the Solid State - The electronic structure of magnetically doped topological insulator Bi1.09Gd0.06Sb0.85Te3 is studied in the vicinity of the Dirac point at various temperatures (above...     

Splitting of the Spectrum of Fermionic Excitations in a Topological Insulator by Charge Fluctuations

JETP Letters - It is shown that the intersite Coulomb interaction of electrons in a topological insulator leads to the splitting of the initial energy structure and to the induction of two bands of...     

Scattering of Electrons between Edge and Two-Dimensional States of a Two-Dimensional Topological Insulator and the Conductivity of the Topological Insulator Strip in a Metallic State

JETP Letters - The lifetime of electrons on edge states of a two-dimensional topological insulator against the background of an allowed two-dimensional band has been determined. It has been shown...     

Dynamic Rearrangements of a Three-Dimensional Topological Structure of a Moving Domain Wall in Magnetic Film in the Presence of Random Perturbations

Physics of the Solid State - Using three-dimensional micromagnetic simulation, the dynamic processes occurring in a domain wall (DW) that moves under the influence of a constant magnetic field in a...     

Microwave Photoresistance of a Two-Dimensional Topological Insulator in a HgTe Quantum Well

JETP Letters - The microwave photoresistance of a two-dimensional topological insulator in a HgTe quantum well with an inverted spectrum has been experimentally studied under irradiation at...     

Modulation of the Dirac Point Band Gap in the Antiferromagnetic Topological Insulator MnBi2Te4 due to the Surface Potential Gradient Change

Journal of Experimental and Theoretical Physics - The possibility of significant modulation of the band gap open at the Dirac point (DP) in the range from 15 to 55 meV for different samples of the...     

非接触法自动测量薄膜厚度

根据白光等厚干涉原理,基于单片机改造的迈氏干涉仪用于自动测量透明薄膜厚度,采用非接触性测量法。当迈克尔逊干涉仪静镜形成的虚像与动镜相交所成的夹角很小时,在光屏上看到彩色干涉条纹,插入薄膜后,光程差改变,彩纹消失。步进电机带动微调手轮转动,当彩纹再次出现,即可得出透明薄膜厚度。     

Visualizing the in-Gap States in Domain Boundaries of Ultra-Thin Topological Insulator Films

Ultra-thin topological insulators provide a platform for realizing many exotic phenomena such as the quantum spin Hall effect, and quantum anomalous Hall effect. These effects or states are characterized by quantized transport behavior of edge states. Experimentally, although these states have been realized in various systems,the temperature for the edge states to be the dominating channel in transport is extremely low, contrary to the fact that the bulk gap is usually in the order of a few tens of milli-electron volts. There must be other in-gap conduction channels that do not freeze out until a much lower temperature. Here we grow ultra-thin topological insulator Bi_2Te_3 and Sb_2Te_3 films by molecular beam epitaxy and investigate the structures of domain boundaries in these films. By scanning tunneling microscopy and spectroscopy we find that the domain boundaries with large rotation angles have pronounced in-gap bound states, through which one-dimensional conduction channels are suggested to form, as visualized by spatially resolved spectroscopy. Our work indicates the critical role played by domain boundaries in degrading the transport properties.     

Criterion of Surface Electron Transport in the Correlated Topological Insulator SmB6

JETP Letters - The galvanomagnetic characteristics of SmB6 single crystals are studied within the temperature range of 1.9?3.6 K at different orientations of the crystal faces. As a result,...     

Magnetically Controlled Electronic Transport Properties of a Ferromagnetic Junction on the Surface of a Topological Insulator

We have investigated the transport properties of the Dirac fermions through a ferromagnetic barrier junction on the surface of a strong topological insulator.The current-voltage characteristic curve and the tunneling conductance are calculated theoretically.Two interesting transport features are predicted:observable negative differential conductances and linear conductances tunable from unit to nearly zero.These features can be magnetically manipulated simply by changing the spacial orientation of the magnetization.Our results may contribute to the development of high-speed switching and functional applications or electrically controlled magnetization switching.     

Spin Resonance in a Quantum Dot at the Edge of a Topological Insulator with the Inclusion of Continuum States

Journal of Experimental and Theoretical Physics - The dynamics of electronic states under the action of a periodic electric field applied to a quantum dot created by magnetic barriers at the...     

以LiF修饰阴极的有机电致发光器件性能的提高

提出了用一种无机半导体的模型来计算有机电致发光器件(OELDs)的J-V特性.通过在金属/有机物界面插入薄LiF层,由此引入的偶极子能极大地降低了电子的注入势垒和OELDs的开启电压.从而,载流子的注入得到了平衡,OELDs的性能得到了较大提高.经过数值计算,发现LiF插入层有一个约为1.5~5.0nm的最优厚度.LiF层太厚或太薄都会提高器件的开启电压、降低器件的性能.结果表明:这一模型可以用来解释OELD通过LiF修饰阴极后性能的提高.     

Role of Interfaces in the Permittivity Tensor of Thin Layers of a Ferromagnetic Metal

JETP Letters - It is known from experimental studies that the components of the permittivity tensor ε depend on layer thicknesses of multilayer thin films, and for nanometer layers, it is...     

结合椭圆偏振光谱与傅里叶红外光谱的宽禁带半导体薄膜光学特性表征（英文）

宽禁带半导体薄膜,包括碳化硅,氮化镓和氧化锌及其化合物以及异构体,带隙普遍在3.2eV以上,一阶声子特征峰在100至1500cm~(-1)之间。确定能带宽度和声子特征峰有很多方法,比如光致发光、拉曼散射、光学透射谱等,我们提出了一种结合椭圆偏振光谱与红外傅里叶反射谱进行传输矩阵分析的方法,能够同时确定从紫外波段(约250nm)到远红外波段(约22000nm)的薄膜材料色散关系和膜厚。我们构建了基于谐振子的光学函数模型,并论证这个模型很适合用于模拟由各种不同波长入射光波造成的共振吸收。     

利用Raman散射光谱研究铜铟镓硒薄膜表面的掺杂调节作用

主要研究了采用溅射后硒化方法制备CIGS(铜铟镓硒)薄膜太阳电池的吸收体材料中的表面层掺杂调节问题。并利用Raman散射谱分析研究了样品表面层特征峰的移用,研究结果表明: CIGS薄膜表面层由富In表面层调节为富CuGa表面层后,Raman特征峰位向高波数移动,表明薄膜表面的Ga含量随之变化,并导致表面能带的相应改变,经计算证实了富CuGa表面层样品较之富In表面层样品具有更高的表面能带,从而改善了以此材料为吸收层的太阳电池器件性能, V_oc提高了74 mV,填充因子上升8％,最终使器件转换效率η相应提高了约2％。提高了V_oc与FF。同时表明Raman散射谱作为一种灵敏的表面表征手段,在研究太阳电池吸收层表面状态时十分有力。