Mott-driven BEC-BCS crossover in a doped spin liquid candidate, kappa-(BEDT-TTF)4Hg2.89Br8

Abstract

The pairing of interacting fermions leading to superfluidity has two limiting regimes: the Bardeen-Cooper-Schrieffer (BCS) scheme for weakly interacting degenerate fermions and the Bose-Einstein condensation (BEC) of bosonic pairs of strongly interacting fermions. While the superconductivity that emerges in most metallic systems is the BCS-like electron pairing, strongly correlated electrons with poor Fermi liquidity can condense into the unconventional BEC-like pairs. Quantum spin liquids harbor extraordinary spin correlation free from order and the superconductivity that possibly emerges by carrier doping of the spin liquids is expected to have a peculiar pairing nature. The present study experimentally explores the nature of the pairing condensate in a doped spin-liquid candidate material and under varying pressure, which changes the electron-electron Coulombic interactions across the Mott critical value in the system. The transport measurements reveal that the superconductivity at low pressures is a BEC-like condensate from a non-Fermi liquid and crosses over to a BCS-like condensate from a Fermi liquid at high pressures. The Nernst-effect measurements distinctively illustrate the two regimes of the pairing in terms of its robustness to the magnetic field. The present Mott tuning of the BEC-BCS crossover can be compared to the Feshbach tuning of the BEC-BCS crossover of fermionic cold atoms.

arXiv comment25 pages, 10 figures

References in corpus (34)

• Quantum Spin Liquids
• Observation of resonance condensation of fermionic atom pairs
• Quantum Spin Liquid States
• Quantum Criticality in Heavy Fermion Metals
• Continuous Quantum Phase Transitions
• Condensation of Pairs of Fermionic Atoms Near a Feshbach Resonance
• Spin Liquid State in an Organic Mott Insulator with Triangular Lattice
• Quantum Spin Liquids
• BCS-BEC Crossover: From High Temperature Superconductors to Ultracold Superfluids
• The Nernst effect in high-$T_c$ superconductors
• Field-induced superconducting phase of FeSe in the BCS-BEC cross-over
• Mott Transition from a Spin Liquid to a Fermi Liquid in the Spin-Frustrated Organic Conductor kappa-(ET)2Cu2(CN)3
• Quantum frustration in organic Mott insulators: from spin liquids to unconventional superconductors
• Superconductivity and the Pseudogap in the two-dimensional Hubbard model
• Unconventional critical behaviour in a quasi-two-dimensional organic conductor
• BCS-BEC Crossover and the Unitary Fermi Gas
• Quantum phases driven by strong correlations
• From high temperature supercondutivity to quantum spin liquid: progress in strong correlation physics
• Nernst effect in metals and superconductors: a review of concepts and experiments
• Revision of model parameters for kappa-type charge transfer salts: an ab initio study
• Superconducting states in frustrating t-J model: A model connecting high-$T_c$ cuprates, organic conductors and Na${}_x$CoO${}_2$
• Gate-controlled BCS-BEC crossover in a two-dimensional superconductor
• Quantum-critical phase out of frustrated magnetism in a strongly correlated metal
• Crossover between BCS Superconductor and Doped Mott Insulator of d-wave Pairing State in Two-Dimensional Hubbard Model
• Gapped magnetic ground state in quantum-spin-liquid candidate $\kappa$-(BEDT-TTF)${}_2$-Cu${}_2$(CN)${}_3$
• Preformed Cooper pairs in layered FeSe-based superconductors
• Mottness in a doped organic superconductor
• Quasi-continuous transition from a Fermi liquid to a spin liquid
• Mottness collapse and statistical quantum criticality
• Superconductivity in the doped quantum spin liquid on the triangular lattice
• Spin-charge-entangled non-Fermi liquid in a candidate material for a doped spin liquid
• Mott correlated states in the underdoped two-dimensional Hubbard model: variational Monte Carlo versus a dynamical cluster approximation
• Extraordinary $\pi$-Electron Superconductivity Emerging from a Quantum Spin Liquid
• Stabilization of vortex-liquid state by strong pairing interaction

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