Superconductivity in the doped quantum spin liquid on the triangular lattice

Abstract

Broad interest in quantum spin liquid (QSL) phases was triggered by the notion that they can be viewed as insulating phases with preexisting electron pairs, such that upon light doping they might automatically yield high temperature superconductivity. Yet despite intense experimental and numerical efforts, definitive evidence showing that doping QSLs leads to superconductivity has been lacking. We address the problem of a lightly doped QSL through a large-scale density-matrix renormalization group study of the t - J model on finite-circumference triangular cylinders with a small but nonzero concentration of doped holes. We provide direct evidences that doping QSL can naturally give rise to d -wave superconductivity. Specifically, we find power-law superconducting correlations with a Luttinger exponent, K s c \u2009≈\u20091, which is consistent with a strongly diverging superconducting susceptibility, $${\\chi }_{sc} \\,\\sim\\, {T}^{-(2\\,-\\,{K}_{sc})}$$ χ s c ~ T − ( 2 − K s c ) as the temperature T \u2009→\u20090. The spin–spin correlations—as in the undoped QSL state—fall exponentially which suggests that the superconducting pair-pair correlations evolve smoothly from the insulating parent state.