Charge and spin transport through normal lead coupled to $s$-wave superconductor and a Majorana zero mode

Fuente: arXiv
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Main Authors: Mao, Yue, Sun, Qing-Feng
Format: Preprint
Published: 2024
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author Mao, Yue
Sun, Qing-Feng
author_facet Mao, Yue
Sun, Qing-Feng
contents Zero-bias charge conductance peak (ZBCCP) is a significant symbol of Majorana zero modes (MZMs). The proximity effect of s-wave superconductor is usually demanded in the fabrication of MZMs. So in transport experiments, the system is inevitably coupled to the s-wave superconductor. Here we study how the ZBCCP is affected by coupling of the s-wave superconductor. The results show that the ZBCCP could be changed into a zero-bias valley due to the coupling of s-wave superconductor, although the conductance at the zero bias still keeps a quantized value $2e^2/h$. So it does not mean no MZM exists when no ZBCCP is experimentally observed. In addition, the spin transport is investigated. Four reflection processes (the normal reflection, spin-flip reflection, normal Andreev reflection, and equal-spin Andreev reflection) usually occur. The reflection coefficients are strongly dependent on the spin direction of the incident electron, and they may be symmetrical or Fano resonance shapes. But the spin conductance always shows a zero-bias peak with the height $e/2π$ regardless of the direction of the spin bias and the coupling strength of the s-wave superconductor. So measuring spin transport properties could be a more reliable method to judge the existence of MZMs.
format Preprint
id arxiv_https___arxiv_org_abs_2410_21703
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Charge and spin transport through normal lead coupled to $s$-wave superconductor and a Majorana zero mode
Mao, Yue
Sun, Qing-Feng
Mesoscale and Nanoscale Physics
Superconductivity
Zero-bias charge conductance peak (ZBCCP) is a significant symbol of Majorana zero modes (MZMs). The proximity effect of s-wave superconductor is usually demanded in the fabrication of MZMs. So in transport experiments, the system is inevitably coupled to the s-wave superconductor. Here we study how the ZBCCP is affected by coupling of the s-wave superconductor. The results show that the ZBCCP could be changed into a zero-bias valley due to the coupling of s-wave superconductor, although the conductance at the zero bias still keeps a quantized value $2e^2/h$. So it does not mean no MZM exists when no ZBCCP is experimentally observed. In addition, the spin transport is investigated. Four reflection processes (the normal reflection, spin-flip reflection, normal Andreev reflection, and equal-spin Andreev reflection) usually occur. The reflection coefficients are strongly dependent on the spin direction of the incident electron, and they may be symmetrical or Fano resonance shapes. But the spin conductance always shows a zero-bias peak with the height $e/2π$ regardless of the direction of the spin bias and the coupling strength of the s-wave superconductor. So measuring spin transport properties could be a more reliable method to judge the existence of MZMs.
title Charge and spin transport through normal lead coupled to $s$-wave superconductor and a Majorana zero mode
topic Mesoscale and Nanoscale Physics
Superconductivity
url https://arxiv.org/abs/2410.21703