Quasi-bound States and Resonant Skew Scattering in Two-Dimensional Materials with a Mexican-Hat Dispersion

Abstract

Mexican-hat dispersion of band electrons in two-dimensional materials attracts a lot of interest, mainly due to the Van Hove singularity of the density of states near the band edge. In this paper, we show that there is one more feature of such a dispersion, which also leads to nontrivial effects. It consists in the fact that the sign of the effective mass in the momentum space near the central extremum is opposite to the sign of the mass outside this region. For this reason, any localized potential that repels quasiparticles in the outer region attracts quasiparticles in the central region and thereby creates quasi-bound states. We study these states in the case when the Mexican-hat dispersion is formed due to the hybridization of the inverted electron and hole bands, and the potential is created by a point defect. The energy and width of the resonance of the local density of states corresponding to a quasi-bound state are found, and it is shown that, under certain conditions, a quasi-bound state can transform into a bound state in a continuum of band states. The presence of quasi-bound states leads to nontrivial effects in the spin-dependent scattering of electrons. Due to the quasi-bound state, the skew scattering is strongly enhanced for electrons with energy near the resonance, and the skewness angle varies over a wide range depending on the energy. In addition, in a certain energy range, a nontrivial effect of scattering suppression appears in the direction opposite to the skewness angle.

9 pages, 5 figures, accepted in Physica E: Low-dimensional Systems and Nanostructures

References in corpus (5)

• Quantum Spin Hall Effect and Topological Phase Transition in HgTe Quantum Wells
• Tunable Magnetism and Half-Metallicity in Hole-doped Monolayer GaSe
• Topological Change of the Fermi Surface in Low Density Rashba Gases: Application to Superconductivity
• Scattering of charge carriers by point defects in bilayer graphene
• Van Hove Singularity Arising from Mexican-Hat-Shaped Inverted Bands in the Topological Insulator Sn-doped Bi${}_{1.1}$Sb${}_{0.9}$Te${}_2$S

Cited by in corpus (5)

• Friedel oscillations in two-dimensional materials with inverted bands and Mexican-hat dispersion
• Quasi-bound Electron Pairs in Two-Dimensional Materials with a Mexican-Hat Dispersion
• Existence of Mexican-hat dispersion and symmetry group of a layer
• Charged impurity scattering in two-dimensional topological insulators with Mexican-hat dispersion
• Interband plasmons due to Mexican hat dispersion in two-dimensional materials with inverted bands