Anomalous quantum scattering and transport of electrons with Mexican-hat dispersion induced by electrical potential
arxiv(2024)
摘要
We theoretically study the quantum scattering and transport of electrons with
Mexican-hat dispersion through both step and rectangular potential barriers by
using the transfer matrix method. Owing to the torus-like iso-energy lines of
the Mexican-hat dispersion, we observe the presence of double reflections and
double transmissions in both two different barrier scenarios, i.e., the normal
reflection (NR), retro-reflection (RR), normal transmission (NT), and specular
transmission (ST).For the step potential with electrons incident from the large
wavevector, the transmission is primarily governed by NT with nearly negligible
ST, while the reflection is dominant by RR (NR) within (outside) the critical
angle. Additionally, for electrons incident from the small wavevector, the NT
can be reduced to zero by adjusting the barrier, resulting in a significant
enhancement of ST and RR. For the rectangular barrier, the transmission and
reflection spectra resemble those of the step barrier, but there are two kinds
of resonant tunneling which can lead to perfect NT or ST. There exists a
negative differential conductance (NDC) effect in the conductance spectrum. The
conductance and the peak-to-valley ratio of the NDC effect can be effectively
controlled by adjusting the height and width of the barrier as well as the
incident energy. Our results provide a deeper understanding of the electron
states governed by the Mexican-hat dispersion.
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