Spin-charge separation and resonant valence bond spin liquid in a kinetically-frustrated lightly-doped Mott insulator
Presented by Claudio Castelnovo, Theory of Condensed Matter Group, Department of Physics, University of Cambridge, Cambridge, UK
Ideas about resonant valence bond liquid 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 and infinite-onsite-repulsion limit of a half-filled Mott insulator on corner-sharing tetrahedral lattices with frustrated hopping. We confirm numerically that the results extend to finite exchange interactions, finite-sized systems and finite dopant density. We further conducted a preliminary study on the nature of the excitations and spin-liquid correlations, suggestive of bosonic holon behaviour. 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 establishing robust, topologically ordered states in real materials
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