Strain-dependent electronic and magnetic properties of MoS2 monolayer, bilayer, nanoribbons and nanotubes
Strain-dependent electronic and magnetic properties of MoS2 monolayer, bilayer, nanoribbons and nanotubes
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MoS2 单层、双层、纳米带和纳米管的应变相关电子和磁性
DOI：
10.1039/c2cp42181j
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发表时间：
2012-01-01
影响因子：
3.3
通讯作者：
Zeng, Xiao Cheng
中科院分区：
文献类型：
--
作者：
Lu, Peng;Wu, Xiaojun;Zeng, Xiao Cheng
我们研究了二维（2D）单层和双层MoS 2，以及一维MoS 2纳米带和纳米管使用第一性原理计算的应变相关的电子和磁性。对于2D单层MoS 2，在各向同性或单轴拉伸应变下，MoS 2的直接带隙转变为间接带隙，并随应变的增加而单调减小;而在压缩应变下，原始直接带隙首先增大，当应变超过-2%时，带隙减小。各向同性应变的影响比单轴应变的影响更大。在各向同性拉伸应变下，双层MoS 2的间接间隙在应变约6%时单调减小为零;而在各向同性压缩应变下，双层MoS 2的间接间隙先增大后减小，当应变超过-4%时转变为直接间隙。对于应变的1D金属锯齿形MoS 2纳米带，净磁矩随着轴向应变从约-5%到5%而略微增加，但是当压缩应变超过-5%时下降到零，或者随着幂律增加超过5%。对于一维扶手椅型MoS 2纳米管，拉伸或压缩轴向应变线性地减小或扩大带隙，对于直径相对较小或在较大拉伸应变下的纳米管，差距可以完全闭合。对于锯齿形MoS 2纳米管，应变效应变为非线性，拉伸应变使带隙减小，而压缩应变使带隙先增大后减小，分析了应变引起的Mo原子投影轨道能量的变化以及Mo原子d轨道与S原子p轨道之间的耦合，解释了强应变对带隙和磁性的影响.
We investigate the strain-dependent electronic and magnetic properties of two-dimensional (2D) monolayer and bilayer MoS2, as well as 1D MoS2 nanoribbons and nanotubes using first-principles calculations. For 2D monolayer MoS2 subjected to isotropic or uniaxial tensile strain, the direct band gap of MoS2 changes to an indirect gap that decreases monotonically with increasing strain; while under the compressive strain, the original direct band gap is enlarged first, followed by gap reduction when the strain is beyond -2%. The effect of isotropic strain is even stronger than that of uniaxial strain. For bilayer MoS2 subjected to isotropic tensile strain, its indirect gap reduces monotonically to zero at strain about 6%; while under the isotropic compressive strain, its indirect gap increases first and then reduces and turns into direct gap when the strain is beyond -4%. For strained 1D metallic zigzag MoS2 nanoribbons, the net magnetic moment increases slightly with axial strain from about -5% to 5%, but drops to zero when the compressive strain is beyond -5% or increases with a power law beyond 5%. For 1D armchair MoS2 nanotubes, tensile or compressive axial strain reduces or enlarges the band gap linearly, and the gap can be fully closed for nanotubes with relatively small diameter or under large tensile strain. For zigzag MoS2 nanotubes, the strain effect becomes nonlinear and the tensile strain can reduce the band gap, whereas compressive strain can initially enlarge the band gap and then decrease it. The strain induced change in projected orbitals energy of Mo and the coupling between the Mo atom d orbital and the S atom p orbital are analyzed to explain the strong strain effect on the band gap and magnetic properties.