A resonant valence bond spin liquid in the dilute limit of doped frustrated Mott insulators

TL;DR

This paper demonstrates the existence of a resonant valence bond spin liquid with spin-charge separation in doped frustrated Mott insulators, revealing a new route to topologically ordered states driven by kinetic energy frustration.

Contribution

It provides an analytical and numerical demonstration of a resonant valence bond phase in realistic Hamiltonians, emphasizing the role of kinetic energy frustration in stabilizing topological order.

Findings

Resonant valence bond phase found in dilute-doping limit

Spin-charge separation observed in the ground state

Kinetic energy frustration stabilizes topological states

Abstract

Ideas about resonant valence bond liquids and spin-charge separation have led to key concepts in physics such as quantum spin liquids, emergent gauge symmetries, topological order, and fractionalisation. Despite extensive efforts to demonstrate the existence of a resonant valence bond phase in the Hubbard model that originally motivated the concept, a definitive realisation has yet to be achieved. Here we present a solution to this long-standing problem by uncovering a resonant valence bond phase exhibiting spin-charge separation in realistic Hamiltonians. We show analytically that this ground state emerges in the dilute-doping limit of a half-filled Mott insulator on corner-sharing tetrahedral lattices with frustrated hopping, in the absence of exchange interactions. We confirm numerically that the results extend to finite exchange interactions, finite-sized systems and finite dopant density. Although much attention has been devoted to the emergence of unconventional states from geometrically frustrated interactions, our work demonstrates that kinetic energy frustration in doped Mott insulators may be essential for stabilising robust, topologically ordered states in real materials.