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arXiv · 1710.10056

Tuning Majorana zero modes with temperature in $π$-phase Josephson junctions

Umberto Borla·Dushko Kuzmanovski·Annica M. Black-Schaffer
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Abstract

We study a superconductor-normal state-superconductor (SNS) Josephson junction along the edge of a quantum spin Hall insulator (QSHI) with a superconducting $π$-phase across the junction. We solve self-consistently for the superconducting order parameter and find both real junctions, where the order parameter is fully real throughout the system, and junctions where the order parameter has a complex phase winding. Real junctions host two Majorana zero modes (MZMs), while phase-winding junctions have no subgap states close to zero energy. At zero temperature we find that the phase-winding solution always has the lowest free energy, which we establish being due to a strong proximity-effect into the N region. With increasing temperature this proximity-effect is dramatically decreased and we find a phase transition into a real junction with two MZMs.

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Umberto Borla, Dushko Kuzmanovski, Annica M. Black-Schaffer. 2018-02-02. Tuning Majorana zero modes with temperature in $π$-phase Josephson junctions. https://doi.org/10.1103/physrevb.97.014507

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