Realizing topological Kondo effect in Fe(Te,Se) based simple mesoscopic device.*

Kondo effect (KE) occurs when conduction electrons couple to local quantum degree of freedom with spin degenerate energy levels. However, symmetry breaking perturbations can destroy this effect. Interestingly a robust topological Kondo effect (TKE) [1, 2] can arise due to coupling between conduction electrons and topologically degenerate Majorana fermions (MF). Here Majorana bound states (MBS) play the role of the quantum impurity spin in KE. The TKE can further result into unique non-Fermi liquid transport signatures. Hence, if such transport signature is realized in experiment, it can contribute to the exploration of MF. One way to realize such TKE is by employing mesoscopic superconducting device that can host MBS. It is known that topological superconductor (TSC) is promising candidate to host MF. Motivated by these, In this work we propose a simple mesoscopic setup made of iron based TSC FeSe_0.45Te_0.55 [3] containing magnetic domain wall, having a solid potential to realize TKE. As it is easy to grow high quality single crystals and thin films of Fe(Te,Se), our proposed device is a lot easier to fabricate as compared to s-wave superconductors based heterostructure devices.  Additionally it will be advantageous, as FeSe_0.45Te_0.55 is intrinsic TSC with a relatively high T_c.

References:

1. B. Beri et.al., PRL 109, 156803 (2012)

2. A. Altland et.al., PRL 113, 076401 (2014)

3. P. Zhang et. al., Science 360, 6385 (2018)