Inverse coherence effects in nuclear magnetic relaxation rates as a sign of topological superconductivity

Abstract

We reveal that three-dimensional multi-orbital topological superconductivity can be identified by a bulk measurement, i.e., the temperature dependence of nuclear magnetic relaxation (NMR) rates. Below a critical temperature $T_{\mathrm{c}}$, the NMR rate in the topological state exhibits an anti-peak profile, which is opposite to the conventional $s$-wave state. This inversion coherence effect comes from a twist of order parameters with respect to orbital and spin degrees of freedom. Our self-consistent calculations in the model for Cu${}_x$Bi${}_2$Se${}_3$ prove that the inverse coherence effect appears as a concave temperature dependence of the NMR rates. We propose that a time-reversal-invariant orbital-singlet spin-triplet topological superconductivity is characterized by the temperature dependence of the NMR rate.

5 pages, 3 figures + Supplemental Material, accepted for publication in Phys. Rev. B as a Rapid Communication

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Cited by in corpus (3)

• Superconducting proximity in three dimensional Dirac materials: odd-frequency, pseudoscalar, pseudovector and tensor-valued superconducting orders
• Nuclear magnetic relaxation rates of unconventional superconductivity in doped topological insulators
• Possible two-component pairings in electron-doped Bi${}_2$Se${}_3$ based on a tight-binding model