Electrical detection of spin liquids in double moir\'e layers

TL;DR

This paper proposes a platform using double moiré layers to electrically detect and study exotic quantum spin liquid phases, overcoming traditional measurement challenges in solid state systems.

Contribution

It introduces a novel experimental setup with Coulomb-coupled moiré layers that enables electrical detection of spin transport and stabilizes various quantum phases including spin liquids.

Findings

Electrical measurement of pseudospin transport is feasible.

The platform realizes Hubbard models with multiple flavors.

Exotic phases like chiral spin liquids are predicted.

Abstract

Although spin is a fundamental quantum number, measuring spin transport in traditional solid state systems is extremely challenging. This poses a major obstacle to detecting interesting quantum states including certain spin liquids. In this paper we propose a platform that not only allows for the electrical measurement of spin transport, but in which a variety of exotic quantum phases may be stabilized. Our proposal involves two moir\'e superlattices, built from transition metal dichalcogenides (TMD) or graphene, separated from one another by a thin insulating layer. The two Coulomb coupled moir\'e layers, when suitably aligned, give rise to a layer pseudospin degree of freedom. The transport of pseudospin can be accessed from purely electrical measurements of counter-flow or Coulomb drag conductivity. Furthermore, these platforms naturally realize Hubbard models on the triangular lattice with $N = 4\, {\rm or}\, 8$ flavors. The flavor degeneracy motivates a large-N approximation from which we obtain the phase diagram of Mott insulators at different electron fillings and correlation strengths. In addition to conventional phases such as psuedospin superfluids and crystallized insulators, exotic phases including chiral spin liquids and a $U(1)$ spinon Fermi surface spin liquid are also found, all of which will show smoking gun electrical signatures in this setup.