Majorana Kramers pair in a nematic vortex

Abstract

A time-reversal (TR) invariant topological superconductor is characterized by a Kramers pair of Majorana zero-energy modes on boundaries and in a core of a TR invariant vortex. A vortex defect that preserves TR symmetry has remained primarily of theoretical interest, since typically a magnetic field, which explicitly breaks TR, needs to be applied to create vortices in superconductors. In this work, we show that an odd-parity topological superconductor with a nematic pairing order parameter can host a nematic vortex that preserves TR symmetry and binds a Majorana Kramers pair. Such a nematic superconductor could be realized in metal-doped Bi${}_2$Se${}_3$, as suggested by recent experiments. We provide an analytic solution for the zero modes in a continuous nematic vortex. In lattice, crystalline anisotropy can pin the two-component order parameter along high-symmetry directions. We show that a discrete nematic vortex, which forms when three nematic domains meet, also supports a TR pair of Majorana modes. Finally, we discuss possible experiments to probe the zero modes.

9 pages, 4 figures

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• Chiral Superconductivity in Thin Films of doped Bi${}_2$Se${}_3$
• Topological superconductor in quasi-one-dimensional Tl2-xMo6Se6
• Magnetic response of nematic superconductors: skyrmion stripes and their signatures in muon spin relaxation experiments
• Symmetries, Length Scales, Magnetic Response and Skyrmion Chains in Nematic Superconductors
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• Strain induced spin vortex and Majorana Kramer's pairs in doped topological insulators with nematic superconductivity
• Possible two-component pairings in electron-doped Bi${}_2$Se${}_3$ based on a tight-binding model
• Anomalous Josephson Hall effect in doped topological insulators with the nematic superconductivity
• Revisiting vestigial order in nematic superconductors: gauge-field mechanisms and model constraints