Topological Superconductivity in Metal/Quantum-Spin-Ice Heterostructures

TL;DR

This paper proposes a novel heterostructure approach using quantum spin ice as a substrate to induce topological odd-parity superconductivity in metallic layers, predicting a transition temperature of a few Kelvin.

Contribution

It introduces a new method to realize topological superconductivity by combining quantum spin liquids with metallic films, enabling controlled interaction engineering.

Findings

Predicts topological odd-parity pairing driven by gauge-electron coupling

Suggests specific heterostructure design using Y2Sn2-xSbxO7 on Pr2Zr2O7

Estimates transition temperature around a few Kelvin

Abstract

The original proposal to achieve superconductivity by starting from a quantum spin-liquid (QSL) and doping it with charge carriers, as proposed by Anderson in 1987, has yet to be realized. Here we propose an alternative strategy: use a QSL as a substrate for heterostructure growth of metallic films to design exotic superconductors. By spatially separating the two key ingredients of superconductivity, i.e., charge carriers (metal) and pairing interaction (QSL), the proposed setup naturally lands on the parameter regime conducive to a controlled theoretical prediction. Moreover, the proposed setup allows us to "customize" electron-electron interaction imprinted on the metallic layer. The QSL material of our choice is quantum spin ice well-known for its emergent gauge-field description of spin frustration. Assuming the metallic layer forms an isotropic single Fermi pocket, we predict that the coupling between the emergent gauge-field and the electrons of the metallic layer will drive topological odd-parity pairing. We further present guiding principles for materializing the suitable heterostructure using ab initio calculations and describe the band structure we predict for the case of Y$_2$Sn$_{2-x}$Sb$_x$O$_7$ grown on the (111) surface of Pr$_2$Zr$_2$O$_7$. Using this microscopic information, we predict topological odd-parity superconductivity at a few Kelvin in this heterostructure, which is comparable to the $T_c$ of the only other confirmed odd-parity superconductor Sr$_2$RuO$_4$.