Thermoelectric transport in junctions of Majorana and Dirac channels

Abstract

We investigate the thermoelectric current and heat conductance in a chiral Josephson contact on a surface of a 3D topological insulator, covered with superconducting and magnetic insulator films. The contact consists of two junctions of Majorana and Dirac channels next to two superconductors. Geometric asymmetry results in a supercurrent without a phase bias. The interference of Dirac fermions causes oscillations of the electric and heat currents with an unconventional period 2Φ0 = h/e as functions of the Aharonov-Bohm flux. Due to the gapless character of Majorana modes, there is no threshold for the thermoelectric effect and the current-flux relationship is non-sinusoidal. Depending on the magnetic flux, the direction of the electric current can be both from the hot to cold lead and vice versa.

Strain-engineered Majorana zero energy modes and φ0 Josephson state in black phosphorus

“…Therefore, by increasing the exchange field, while ϕ 0 is enhanced, the amplitude of the total current is exponentially suppressed. The ϕ 0 Josephson state was also discussed in other contexts 39,[63][64][65][66] and recently realized in experiment [67][68][69] . In Fig.…”

“…The experimental observations showed zero energy peaks through tunneling experiments, and this zero-bias mode was attributed to the presence of Majorana fermions, although not conclusively [27][28][29][30][31][35][36][37] . There are also other ongoing efforts using, for example, thermal Hall conductance to observe the Majorana fermions [38][39][40] . The experi-ments revealed fractional conductance at a filling factor of 5/2 in quantum Hall states, providing a signature of non-Abelian states.…”

Spontaneous supercurrent and φ0 phase shift parallel to magnetized topological insulator interfaces

“…It is worth mentioning that the appearance of a ϕ0 phase shift in the supercurrent has theoretically been discussed in various situations 13,16,26,27,[62][63][64][65][66][67][68][69][70][71][72] and observed in experiments 73,74 . In structures where the spin orbit meditated coupling is available, its interplay with a properly oriented Zeeman(-like) field results in a supercurrent flow perpendicular to the junction interfaces at zero phase difference 13,16,26,27,71,72 . Figure 3(b) illustrates the current densities along the A and B trajectories where the magnetizations in both sides of the weak-link are nonzero.…”

Self-biased current, magnetic interference response, and superconducting vortices in tilted Weyl semimetals with disorder

“…(10) (in the diffusive regime 63,64 ) together with proper boundary conditions (11) and substitute the resultant Green's function into Eq. (12). In the diffusive regime, the Usadel equation (10) results in nonliner boundary value differential equations that has to be solved numerically 79 .…”

“…Also, the band touching points of Weyl semimetals are the so-called Weyl nodes where the Fermi surface, encompassing the nodes, has a nonzero Chern number, thus topologically is nontrivial. The interplay of topological phase with superconductivity is expected to result in topological superconductivity, hosting Majorana fermions governed by non-Abeian statistics [11][12][13] .…”