Beyond the standard model of topological Josephson junctions: From crystalline anisotropy to finite-size and diode effects

Abstract

A planar Josephson junction is a versatile platform to realize topological superconductivity over a large parameter space and host Majorana bound states. With a change in Zeeman field, this system undergoes a transition from trivial to topological superconductivity accompanied by a jump in the superconducting phase difference between the two superconductors. A standard model of these Josephson junctions, which can be fabricated to have a nearly perfect interfacial transparency, predicts a simple universal behavior. In that model, at the same value of Zeeman field for the topological transition, there is a $\pi$ phase jump and a minimum in the critical superconducting current, while applying a controllable phase difference yields a diamond-shaped topological region as a function of that phase difference and a Zeeman field. In contrast, even for a perfect interfacial transparency, we find a much richer and nonuniversal behavior as the width of the superconductor is varied or the Dresselhaus spin-orbit coupling is considered. The Zeeman field for the phase jump, not necessarily $\pi$, is different from the value for the minimum critical current, while there is a strong deviation from the diamond-like topological region. These Josephson junctions show a striking example of a nonreciprocal transport and superconducting diode effect, revealing the importance of our findings not only for topological superconductivity and fault-tolerant quantum computing, but also for superconducting spintronics.

Invited to APL Special Topic Issue: "Josephson Junctions and Related Proximity Effects: From Basic Science to Emerging Applications in Advanced Technologies", accepted version

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Cited by in corpus (6)

• Superconducting diode efficiency from singlet-triplet mixing in disordered systems
• Microwave Signatures of Topological Superconductivity in Planar Josephson Junctions
• Disorder effects in planar semiconductor-superconductor structures: Majorana wires versus Josephson junctions
• Microwave Andreev bound state spectroscopy in a semiconductor-based Planar Josephson junction
• Planar Josephson junction devices with narrow superconducting strips: Topological properties and optimization
• Majorana edge and end states in planar Josephson junctions