Applying BCS-BEC Crossover Theory To High Temperature Superconductors and Ultracold Atomic Fermi Gases

Abstract

This review is written at the time of the twentieth anniversary of the discovery of high temperature superconductors, which, nearly coincides with the important discovery of the superfluid phases of ultracold trapped fermionic atoms. We show how these two subjects have much in common. Both have been addressed from the perspective of the BCS-Bose Einstein condensation (BEC) crossover scenario, which is designed to treat short coherence length superfluids with transition temperatures which are "high", with respect to the Fermi energy. A generalized mean field treatment of BCS-BEC crossover at general temperatures $T$, based on the BCS-Leggett ground state, has met with remarkable success in the fermionic atomic systems. Here we summarize this success in the context of four different cold atom experiments, all of which provide indications, direct or indirect, for the existence of a pseudogap. This scenario also provides a physical picture of the pseudogap phase in the underdoped cuprates which is a central focus of high $T_c$ research. We summarize successful applications of BCS-BEC crossover to key experiments in high $T_c$ systems including the phase diagram, specific heat, and vortex core STM data, along with the Nernst effect, and exciting recent data on the superfluid density in very underdoped samples,

Review article for the 20th anniversary of high Tc superconductivity, 20 pages, 25 figures, to appear in J Low Temp Phys

References in corpus (11)

• Observation of Bose-Einstein Condensation of Molecules
• Observation of the Pairing Gap in a Strongly Interacting Fermi Gas
• Crossover from a molecular Bose-Einstein condensate to a degenerate Fermi gas
• Weakly bound dimers of fermionic atoms
• Collective excitations of a degenerate gas at the BEC-BCS crossover
• Molecular Probe of Pairing in the BEC-BCS Crossover
• Heat Capacity of a Strongly-Interacting Fermi Gas
• Pure Gas of Optically Trapped Molecules Created from Fermionic Atoms
• Collective modes and ballistic expansion of a Fermi gas in the BCS-BEC crossover
• Radio frequency spectroscopy and the pairing gap in trapped Fermi gases
• The pseudogap state in superconductors: Extended Hartree approach to time-dependent Ginzburg-Landau Theory

Cited by in corpus (29)

• Resonating valence bonds and mean-field d-wave superconductivity in graphite
• Shallow pockets and very strong coupling superconductivity in FeSe_xTe_1-x
• Quantum Noise Analysis of Spin Systems Realized with Cold Atoms
• Dynamical mean-field theory and numerical renormalization group study of superconductivity in the attractive Hubbard model
• Local origin of the pseudogap in the attractive Hubbard model
• Stability conditions and phase diagrams for two component Fermi gases with population imbalance
• Pseudogap phenomena in ultracold atomic Fermi gases
• Theory of Superfluids with Population Imbalance: Finite Temperature and BCS-BEC Crossover Effects
• Instability of Fulde-Ferrell-Larkin-Ovchinnikov states in three and two dimensions
• Probing the BCS-BEC crossover with persistent currents
• Finite Temperature Momentum Distribution of a Trapped Fermi Gas
• Quasiparticle excitations and dynamic susceptibilities in the BCS-BEC crossover
• Imbalanced d-wave superfluids in the BCS-BEC crossover regime at finite temperatures
• Local Photoemission Spectra and Effects of Spatial Inhomogeneity in the BCS-BEC Crossover Regime of a Trapped Ultracold Fermi Gas
• Cosmological Condensation of Scalar Fields -- Making a dark energy
• Superconducting fluctuations in FeSe${}_{0.5}$Te${}_{0.5}$ thin films probed via microwave spectroscopy
• Bound States and Superconductivity in Dense Fermi Systems
• A new many-body wave function for BCS-BEC crossover in Fermi gases
• Effect of the particle-hole channel on BCS--Bose-Einstein condensation crossover in atomic Fermi gases
• Zero density limit extrapolation of the superfluid transition temperature in a unitary atomic Fermi gas on a lattice
• A Holographic Model for Pseudogap in BCS-BEC Crossover (I): Pairing Fluctuations, Double-Trace Deformation and Dynamics of Bulk Bosonic Fluid
• Stability of nodal quasiparticles in underdoped YBa2Cu3O6+y probed by penetration depth and microwave spectroscopy
• Fermionic superfluidity: From high Tc superconductors to ultracold Fermi gases
• HTSC Cuprate Phase Diagram Using a Modified Boson-Fermion-Gossamer Model Describing Competing Orders, a Quantum Critical Point and Possible Resonance Complex
• A negative-U interpretation of the femto-second laser pulse induced crystallographic expansion of a cuprate HTSC material reported recently by Gedik et al
• Evolution with hole doping of the electronic excitation spectrum in the cuprate superconductors
• Radio Frequency Response of the Strongly Interacting Fermi Gases at Finite Temperatures
• What can ultracold Fermi gases teach us about high $T_c$ superconductors and vice versa?
• Underdoped cuprates, manifestations of boson-fermion crossover, `quantum oscillations' and the robust fractional quantum Hall state nu = 2/5