Magic gap ratio for optimally robust fermionic condensation and its implications for high-Tc superconductivity

Abstract

Bardeen-Schrieffer-Cooper (BCS) and Bose-Einstein condensation (BEC) occur at opposite limits of a continuum of pairing interaction strength between fermions. A crossover between these limits is readily observed in a cold atomic Fermi gas. Whether it occurs in other systems such as the high temperature superconducting cuprates has remained an open question. We uncover here unambiguous evidence for a BCS-BEC crossover in the cuprates by identifying a universal magic gap ratio 2Δ/k_BT_c ~ 6.5 (where Δis the pairing gap and Tc is the transition temperature) at which paired fermion condensates become optimally robust. At this gap ratio, corresponding to the unitary point in a cold atomic Fermi gas, the condensate fraction N_0 and the height of the jump δγ(Tc) in the coefficient γof the fermionic specific heat at Tc are strongly peaked. In the cuprates, δγ(Tc) is peaked at this gap ratio when Δcorresponds to the antinodal spectroscopic gap, thus reinforcing its interpretation as the pairing gap. We find the peak in δγ(Tc) also to coincide with a normal state maximum in γ, which is indicative of a pairing fluctuation pseudogap above Tc.

arXiv comment15 pages including 8 figures

References in corpus (78)

• Many-Body Physics with Ultracold Gases
• Angle-resolved photoemission spectroscopy of the cuprate superconductors
• The pseudogap in high-temperature superconductors: an experimental survey
• Theory of ultracold Fermi gases
• Observation of resonance condensation of fermionic atom pairs
• Condensation of Pairs of Fermionic Atoms Near a Feshbach Resonance
• Hidden Order in the Cuprates
• Theory of Intertwined Orders in High Temperature Superconductors
• Destruction of the Fermi Surface in Underdoped High Tc Superconductors
• Observation of Bose-Einstein Condensation of Molecules
• Tunable Phase Boundaries and Ultra-Strong Coupling Superconductivity in Mirror Symmetric Magic-Angle Trilayer Graphene
• Observation of the Pairing Gap in a Strongly Interacting Fermi Gas
• BCS-BEC Crossover: From High Temperature Superconductors to Ultracold Superfluids
• Revealing the Superfluid Lambda Transition in the Universal Thermodynamics of a Unitary Fermi Gas
• Electron pockets in the Fermi surface of hole-doped high-Tc superconductors
• The Physics of Pair Density Waves
• Two Gaps Make a High Temperature Superconductor?
• Optically enhanced coherent transport in YBa2Cu3O6.5 by ultrafast redistribution of interlayer coupling
• Field-induced superconducting phase of FeSe in the BCS-BEC cross-over
• A Theory of the Pseudogap State of the Cuprates
• Evaluation of CuO2 plane hole doping in YBa2Cu3O6+x single crystals
• Thermodynamics of the BCS-BEC crossover
• Universal Quantum Viscosity in a Unitary Fermi Gas
• Resonant X-ray Scattering Study of Charge Density Wave Correlations in YBa${}_2$Cu${}_3$O${}_{6+x}$
• Observation of pseudogap behavior in a strongly interacting Fermi gas
• Diamagnetism and Cooper pairing above $T_c$ in cuprates
• Universal $T$-linear resistivity and Planckian limit in overdoped cuprates
• Optically induced coherent transport far above Tc in underdoped YBa2Cu3O6+x
• BCS-BEC Crossover and the Unitary Fermi Gas
• The BCS-BEC crossover: From ultra-cold Fermi gases to nuclear systems
• Quenched disorder and vestigial nematicity in the pseudo-gap regime of the cuprates
• Direct measurement of the upper critical field in a cuprate superconductor
• Thermal Conductivity across the Phase Diagram of Cuprates: Low-Energy Quasiparticles and Doping Dependence of the Superconducting Gap
• Competing charge, spin, and superconducting orders in underdoped YBa2Cu3Oy
• Quasiparticle mass enhancement approaching optimal doping in a high-Tc superconductor
• Thermodynamic signatures of quantum criticality in cuprates
• Determination of the Superfluid Gap in Atomic Fermi Gases by Quasiparticle Spectroscopy
• Towards resolution of the Fermi surface in underdoped high-Tc superconductors
• Scale-invariant magnetoresistance in a cuprate superconductor
• Planckian dissipation, minimal viscosity and the transport in cuprate strange metals
• Microscopic theory of weak pseudogap behavior in the underdoped cuprate superconductors I: General theory and quasiparticle properties
• A Phenomenological Theory of the Anomalous Pseudogap Phase in Underdoped Cuprates
• Single-particle properties and pseudogap effects in the BCS-BEC crossover regime of an ultracold Fermi gas above Tc
• Evidence of precursor superconductivity as high as 180 K from infrared spectroscopy
• Evolution of the Normal State of a Strongly Interacting Fermi Gas from a Pseudogap Phase to a Molecular Bose Gas
• Gate-controlled BCS-BEC crossover in a two-dimensional superconductor
• Crossover from weak to strong pairing in unconventional superconductors
• Pseudogap above Tc in a model with d_{x^2-y^2} pairing
• Upper bounds on the superfluid stiffness and superconducting $T_c$: Applications to twisted-bilayer graphene and ultra-cold Fermi gases
• Carrier-Concentration Dependence of the Pseudogap Ground State of Superconducting Bi2Sr2-xLaxCuO6+delta Revealed by 63,65Cu-Nuclear Magnetic Resonance in Very High Magnetic Fields
• Electron pairing in the pseudogap state revealed by shot noise in copper-oxide junctions
• Disorder, Metal-Insulator crossover and Phase diagram in high-Tc cuprates
• Quantum mechanical limitations to spin diffusion in the unitary Fermi gas
• Specific-Heat Measurement of Residual Superconductivity in the Normal State of Underdoped Cuprate Superconductors
• Onset of a Pseudogap Regime in Ultracold Fermi Gases
• Evidence for a Vestigial Nematic State in the Cuprate Pseudogap Phase
• Effect of the pseudogap on T${}_c$ in the cuprates and implications for its origin
• Gapless superconductivity and the Fermi arc in the cuprates
• Superconducting phase coherence in the presence of a pseudogap: Relation to specific heat, tunneling and vortex core spectroscopies
• Electronic Duality in Strongly Correlated Matter
• Thermodynamics and Phase Diagram of High Temperature Superconductors
• Quantum critical transport in the unitary Fermi gas
• Uniform spin susceptibility and spin-gap phenomenon in the BCS-BEC crossover regime of an ultracold Fermi gas
• Pseudogap phenomena in ultracold atomic Fermi gases
• Gap equation with pairing correlations beyond mean field and its equivalence to a Hugenholtz-Pines condition for fermion pairs
• Specific heat of underdoped cuprates: RVB versus Fermi arcs
• Pairing correlations across the superfluid phase transition in the unitary Fermi gas
• Emergence of a pseudogap in the BCS-BEC crossover
• Phenomenological Ginzburg-Landau-like theory for superconductivity in the cuprates
• Specific heat and effects of pairing fluctuations in the BCS-BEC crossover regime of an ultracold Fermi gas
• Optical conductivity of granular aluminum films near the Mott metal-to-insulator transition
• Parallel Spin Stripes and Their Coexistance with Superconducting Ground States at Optimal and High Doping in La${}_{1.6-x}$Nd${}_{0.4}$Sr${}_x$CuO${}_4$
• NMR Studies of pseudogap and electronic inhomogeneity in Bi${}_2$Sr${}_2$CaCu${}_2$O${}_{8+\delta }$
• Extent of Fermi-surface reconstruction in the high-temperature superconductor HgBa${}_2$CuO${}_{4+\delta }$
• Theory of the Fermi Arcs, the Pseudogap, $T_c$ and the Anisotropy in k-space of Cuprate Superconductors
• Generalization of BCS theory to short coherence length superconductors: A BCS--Bose-Einstein crossover scenario
• How 'pairons' are revealed in the electronic specific heat of cuprates
• Tuning across the BCS-BEC crossover in the multiband superconductor Fe${}_{1+y}$Se${}_x$Te${}_{1-x}$ : An angle-resolved photoemission study

Cited by in corpus (8)

• When Superconductivity Crosses Over: From BCS to BEC
• Absence of a BCS-BEC crossover in the cuprate superconductors
• Andreev reflection spectroscopy in strongly paired superconductors
• Pseudogap formation in organic superconductors
• Test for BCS-BEC Crossover in the Cuprate Superconductors
• Topological two-band electron-hole superconductors with $d$-wave symmetry: Absence of Dirac quasiparticle annihilation in magic-angle twisted trilayer graphene
• Quantum Monte Carlo study of the metal-insulator crossover in the square-lattice Hubbard model
• Tunneling spectra of unconventional quasi-two-dimensional superconductors