Anomalous metallic behaviour in the doped spin liquid candidate κ-(ET)4Hg2.89Br8

Abstract

Quantum spin liquids are exotic Mott insulators that carry extraordinary spin excitations. Therefore, when doped, they are expected to afford metallic states with unconventional magnetic excitations. Here, we report experimental results which are suggestive of a doped spin liquid with anomalous metallicity in a triangular-lattice organic conductor. The spin susceptibility is nearly perfectly scaled to that of a non-doped spin liquid insulator in spite of the metallic state. Furthermore, the charge transport that is confined in the layer at high temperatures becomes sharply deconfined on cooling, coinciding with the rapid growth of spin correlations or coherence as signified by a steep decrease in spin susceptibility. The present results substantiate the desired doped spin liquid and suggest a strange metal, in which the coherence of the underlying spin liquid promotes the deconfinement of charge from the layers while preserving the non-Fermi-liquid nature.

Dimensional decoupling at continuous quantum critical Mott transitions

“…All these features agree with the predictions of our theory on the metallic side qualitatively. Reference [7] also suggested, similar to the considerations in this paper, that the metallic behavior of out-of-plane transport when the in-plane transport is non-Fermi-liquid like is due to the recombination of charge and spin.…”

“…Recently out-of-plane transport of a layered quasi-2D doped organic compound has been studied experimentally [7]. This material is suggested to be a candidate of a doped spin liquid, in the sense that charge and spin will be separated in the absence of doping.…”

“…Very recent experiments have studied interlayer transport in the doped triangular lattice κ-ET organic metals [7], and our results should be a useful guide to their interpretation. Reference [7] found the intralayer transport appears to be nonFermi-liquid like at ambient pressure and becomes Fermiliquid like under high enough pressure.…”

“…Reference [7] found the intralayer transport appears to be nonFermi-liquid like at ambient pressure and becomes Fermiliquid like under high enough pressure. As the temperature is decreased in the non-Fermi-liquid regime, the interlayer resistivity first increases when the temperature is high.…”

“…Examples of "non-Fermi-liquid" metals found experimentally include heavy-fermion compounds, the cuprates, and some organic salts [1][2][3][4][5][6][7].…”