Non-fragile superconductivity with nodes in the superconducting topological insulator CuxBi2Se3: Zeeman orbital field and non-magnetic impurities

Abstract

We study the robustness against non-magnetic impurities in the topological superconductor with point nodes, focusing on an effective model of Cu${}_x$Bi${}_2$Se${}_3$. We find that the topological superconductivity with point-nodes is not fragile against non-magnetic impurities, although the superconductivity with nodes in past studies is usually fragile. Exchanging the role of spin with the one of orbital, and vice versa, we find that in the "dual" space the topological superconductor with point-nodes is regarded as the intra-orbital spin-singlet $s$-wave one. From the viewpoint of the dual space, we deduce that the point-node state is not fragile against non-magnetic impurity, when the orbital imbalance in the normal states is small. Since the spin imbalance is induced by the Zeeman magnetic field, we shall name this key quantity for the impurity effects Zeeman "orbital" field. The numerical calculations support that the deduction is correct. If the Zeeman orbital field is small, the topological superconductivity is not fragile in dirty materials, even with nodes. Thus, the topological superconductors can not be simply regarded as one of the conventional unconventional superconductors.

4 pages, 4 figures. Accepted for publication in PRB Rapid Communications

References in corpus (10)

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• Quantum Spin Hall Insulator State in HgTe Quantum Wells
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• Surface spectral function in the superconducting state of a topological insulator
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• Field-angle-dependent low-energy excitations around a vortex in the superconducting topological insulator CuxBi2Se3

Cited by in corpus (11)

• Unconventional Superconductivity
• Nematic superconductivity in doped Bi2Se3 topological superconductors
• Evidence of nodes in the order parameter of the superconducting doped topological insulator Nb${}_x$Bi${}_2$Se${}_3$ via penetration depth measurements
• Superconducting doped topological materials
• Superconductivity, pairing symmetry, and disorder in the doped topological insulator Sn${}_{1-x}$In${}_x$Te for x $\ge$ 0.10
• Nematic superconductivity in Cu${}_x$Bi${}_2$Se${}_3$: The surface Andreev bound states
• Superconductivity in Cu-doped Bi${}_2$Se${}_3$ with potential disorder
• Bound states around impurities in a superconducting bilayer
• Superconducting and normal-state anisotropy of the doped topological insulator Sr${}_{0.1}$Bi${}_2$Se${}_3$
• Possible two-component pairings in electron-doped Bi${}_2$Se${}_3$ based on a tight-binding model
• Sensitivity of superconducting states to the impurity location in layered materials