A variational Monte Carlo study of the four-band extended Hubbard model finds BCS-BEC crossover at hole doping δ=0.06, while Mott and stripe phases mask it at other dopings.
Reduced superfluid density in a doped spin liquid candidate
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abstract
A quantum spin liquid (QSL) would be an exotic stage for superconductivity. A promising candidate for a doped QSL is the organic triangular-lattice system, kappa-(BEDT-TTF)4Hg2:89Br8, which hosts a non-Fermi liquid and magnetism of a QSL nature and shows superconductivity upon cooling. Here, we report that its superfluid density is anomalously reduced, indicating the existence of substantial incoherent spectral weight and weak superconducting phase stiffness. Moreover, the ratio of the superconducting transition temperature to the nominal Fermi temperature is as large as 0.1, orders of magnitude beyond typical BCS values. These observations in a system free from competing orders that complicate the similar issue in underdoped cuprates give a clue to the enigmatic missing superfluid density in doped Mott insulators.
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cond-mat.supr-con 1years
2024 1verdicts
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Possibility of BCS-BEC crossover in $\kappa$-type organic superconductors
A variational Monte Carlo study of the four-band extended Hubbard model finds BCS-BEC crossover at hole doping δ=0.06, while Mott and stripe phases mask it at other dopings.