Díaz-Fernández Álvaro, Del Valle Natalia, Domínguez-Adame Francisco
GISC, Departamento de Física de Materiales, Universidad Complutense, E-28040 Madrid, Spain.
Beilstein J Nanotechnol. 2018 May 14;9:1405-1413. doi: 10.3762/bjnano.9.133. eCollection 2018.
Several IV-VI semiconductor compounds made of heavy atoms, such as Pb Sn Te, may undergo band-inversion at the point of the Brillouin zone upon variation of their chemical composition. This inversion gives rise to topologically distinct phases, characterized by a change in a topological invariant. In the framework of the · theory, band-inversion can be viewed as a change of sign of the fundamental gap. A two-band model within the envelope-function approximation predicts the appearance of midgap interface states with Dirac cone dispersions in band-inverted junctions, namely, when the gap changes sign along the growth direction. We present a thorough study of these interface electron states in the presence of crossed electric and magnetic fields, the electric field being applied along the growth direction of a band-inverted junction. We show that the Dirac cone is robust and persists even if the fields are strong. In addition, we point out that Landau levels of electron states lying in the semiconductor bands can be tailored by the electric field. Tunable devices are thus likely to be realizable, exploiting the properties studied herein.
几种由重原子构成的IV-VI族半导体化合物，如Pb Sn Te，在其化学成分发生变化时，可能会在布里渊区的Γ点发生能带反转。这种反转会产生拓扑性质不同的相，其特征是拓扑不变量发生变化。在该理论框架下，能带反转可被视为基本能隙符号的改变。包络函数近似下的双带模型预测，在能带反转结中，即当能隙沿生长方向改变符号时，会出现具有狄拉克锥色散的带隙中间界面态。我们对存在交叉电场和磁场时的这些界面电子态进行了深入研究，其中电场沿能带反转结的生长方向施加。我们表明，即使场很强，狄拉克锥也是稳健的且持续存在。此外，我们指出，半导体能带中的电子态的朗道能级可以通过电场进行调控。因此，利用本文所研究的性质，可调谐器件很可能是可实现的。
