Group delay time and Hartman effect in strained Weyl semimetals

The group delay time was theoretically studied in Weyl semimetals (WSMs) in the presence of strain. The Hartman effect, where the delay time for tunneling through a barrier tends to a constant for large barrier thickness, can be observed in WSMs when the incident angles gamma and phi, and the unidirectional strain tensor u(33) and shear strain tensor u(32), are larger than some critical values. We show that the Hartman effect is strongly dependent on the strength of the unidirectional strain tensor u(33) and the ratio of the shear strain tensor u(32)/u(31). We also found that tensile and compressive strains have different effects on the group delay time and the transmission probability T in WSMs. Our study shows the possibility of modulating the group delay time and the Hartman effect in strained WSMs.