Super-Klein tunneling through a rectangular barrier in multi-Weyl semimetals

Recently, three-dimensional Weyl semimetals with topological charge J=1 have attracted a surge of interest in condensed matter physics. However, multi-Weyl semimetals (MSMs) are allowed to have J>1 and, consequently, the dispersions become linear exclusively in one momentum direction, and exhibit a power law dependence (governed by J) in other two directions. We theoretically study the transport through a rectangular potential barrier, perpendicular to the z-axis, created across a junction between two MSMs. Most strikingly, we find that perfect transmission of omnidirectional particles occurs when the incident energy (E) equals to half of the barrier-height (U), which gives rise to the super-Klein tunneling. On the other hand, the Klein tunneling at normal incidence and the Fabry-Perot-like transmission resonance at oblique incidence emerges for all values of J, when E<U as well as E>U. Remarkably, the super-Klein tunneling disappears as soon as the topological charge differs at two sides of the barrier. Several J-dependent effects emerge in thick as well as thin barrier limits, which could be tested in simple experiments.