Strain-Controlled Current Switching in Weyl Semimetals
S. M. Rafi‐Ul‐Islam, Zhuo Bin Siu, Chi Sun, M. B. A. Jalil
Abstract
Applying strain to a Weyl semimetal (WSM) breaks its lattice symmetry and results in a valley-dependent strain gauge potential. Here, we investigate the application of the strain potential to modulate the valley and charge transport of a WSM-based $n$-$p$-$n$ junction system. The strain potential, in combination with insulating barriers, enables modulation of the current and the realization of valley-asymmetric transmission with a high on:off ratio. By considering the geometric optics of electron waves and the transverse displacement of Fermi surfaces due to the strain gauge, we derive the critical strains for switching the current, as well as for the onset of complete angular separation of the two valley currents. The analytical results are verified by numerical calculations of the tunneling transmission and conductance. We also derive the expression for the subthreshold swing of the device, which can achieve values below the thermionic limit by tuning the strain and barrier height.