Spin-charge-entangled non-Fermi liquid in a candidate material for a doped spin liquid

TL;DR

This paper reports on a novel non-Fermi liquid state in a doped spin liquid candidate material, where charge deconfinement and spin-charge entanglement occur simultaneously, revealing new physics in quantum spin liquids.

Contribution

It uncovers a new type of non-Fermi liquid with intertwined spin and charge degrees of freedom in a doped spin liquid material.

Findings

Charge deconfinement occurs sharply at low temperatures.

Spin susceptibility decreases steeply, indicating spin-charge separation.

The observed phenomena suggest a novel spin-charge entangled non-Fermi liquid.

Abstract

Quantum spin liquids are exotic Mott insulators that carry extraordinary spin excitations and thus, when doped, expected to afford novel metallic states coupled to the unconventional magnetic excitations. The organic triangular-lattice system k-(ET)4Hg2.89Br8 is a promising candidate for the doped spin-liquid and hosts a non-Fermi liquid at low pressures. We show that, in the non-Fermi liquid regime, the charge transport confined in the layer gets deconfined sharply at low temperatures, coinciding with the entrance of spins into a quantum regime as signified by a steep decrease in spin susceptibility behaving like the triangular-lattice Heisenberg model indicative of spin-charge separation at high temperatures. This suggests a new type of non-Fermi liquid, where interlayer charge-deconfimement is associated with spin-charge entanglement.