Low temperature thermal transport at the interface of a topological insulator and a d-wave superconductor

Abstract

We consider the low-temperature thermal transport properties of the 2D proximity-induced superconducting state formed at the interface between a 3D strong topological insulator (TI) and a d-wave superconductor (dSC). This system is a playground for studying massless Dirac fermions, as they enter both as quasiparticles of the dSC and as surface states of the TI. For TI surface states with a single Dirac point, the four nodes in the interface-state quasiparticle excitation spectrum coalesce into a single node as the chemical potential, $\mu$, is tuned from above the impurity scattering rate ($|\mu |\gg {\Gamma }_0$) to below ($|\mu |\ll {\Gamma }_0$). We calculate, via Kubo formula, the universal limit ($T\to 0$) thermal conductivity, ${\kappa }_0$, as a function of $\mu$, as it is tuned through this transition. In the large and small $|\mu |$ limits, we obtain disorder-independent, closed-form expressions for ${\kappa }_0/T$. The large-$|\mu |$ expression is exactly half the value expected for a d-wave superconductor, a demonstration of the sense in which the TI surface topological metal is half of an ordinary 2D electron gas. Our numerical results for intermediate $|\mu |$ illustrate the nature of the transition between these limits, which is shown to depend on disorder in a well-defined manner.

12 pages, 5 figures

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Cited by in corpus (5)

• Weak Localization and Antilocalization in Topological Materials with Impurity Spin-Orbit Interactions
• Phase-tunable thermal rectification in the topological SQUIPT
• Anomalous Hall Coulomb drag of massive Dirac fermions
• Coulomb drag in topological insulator films
• Coulomb drag in topological materials