Detecting the fingerprints of Majorana quasiparticles

In a recent Journal of Physics: Condensed Matter paper, Dr Ireneusz Weymann theoretically investigates how Majorana modes effect thermoelectric properties of a quantum dot. Find out more from Dr Weymann in his own words:

Majorana fermions are peculiar particles which are their own antiparticles. Although the existence of such elementary particles is still under debate, it turns out that zero-energy modes of some exotic materials exhibit similar properties. In fact, the signatures of Majorana zero-energy modes have recently been reported experimentally by several groups. Such Majorana quasiparticles can emerge, for example, at the ends of topological superconducting nanowires, and can be detected by attaching a quantum dot to the end of the wire. It transpires that the Majorana zero-energy mode can leak into the quantum dot, resulting in a fractional value of the conductance through the dot.

majorana modes

Figure: The schematic of a quantum dot (QD) coupled to ferromagnetic contacts and side-coupled to topological superconductor (TS) hosting Majorana zero-energy modes. Taken from J. Phys. Cond. Mat 29 095301, © IOP Publishing, 2017. All rights reserved.

Here, we theoretically analyze the effects of Majorana quasiparticles on the thermoelectric properties of a quantum dot attached to ferromagnetic electrodes. Our calculations are performed by using the powerful numerical renormalization group method, which permits very accurate numerical results. We study low-temperature transport in the Kondo regime and demonstrate that transport characteristics generally reveal a subtle interplay between energy scales related to the Kondo, ferromagnetic, and Majorana correlations. In particular, we show that the Seebeck and spin-Seebeck coefficients exhibit additional peaks for temperatures corresponding to the strength of coupling to Majorana wire. Furthermore, we demonstrate that additional sign changes can occur in the temperature dependence of the thermopower in the presence of Majorana fermions. Our findings can demonstrate another fingerprint of Majorana quasiparticles in mesoscopic solid state devices.


Weymann

Dr Weymann is an Associate Professor at the Mesoscopic Physics Division, Adam Mickiewicz University, Poznań, Poland.

 


This work is licensed under a Creative Commons Attribution 3.0 Unported License



Categories: Journal of Physics: Condensed Matter, JPhys+

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