Origin of the pseudogap phase: Precursor superconductivity versus a competing energy gap scenario

Abstract

In the last few years evidence has been accumulating that there are a multiplicity of energy scales which characterize superconductivity in the underdoped cuprates. In contrast to the situation in BCS superconductors, the phase coherence temperature Tc is different from the energy gap onset temperature T*. In addition, thermodynamic and tunneling spectroscopies have led to the inference that the order parameter ${\Delta }_{sc}$ is to be distinguished from the excitation gap $\Delta$; in this way, pseudogap effects persist below Tc. It has been argued by many in the community that the presence of these distinct energy scales demonstrates that the pseudogap is unrelated to superconductivity. In this paper we show that this inference is incorrect. We demonstrate that the difference between the order parameter and excitation gap and the contrasting dependences of T* and Tc on hole concentration $x$ and magnetic field $H$ follow from a natural generalization of BCS theory. This simple generalized form is based on a BCS-like ground state, but with self consistently determined chemical potential in the presence of arbitrary attractive coupling $g$. We have applied this mean field theory with some success to tunneling, transport, thermodynamics and magnetic field effects. We contrast the present approach with the phase fluctuation scenario and discuss key features which might distinguish our precursor superconductivity picture from that involving a competing order parameter.

4 pages, 2 EPS figures, use LaTeX package espcrc2.sty from Elsevier, submitted to SNS'01 conference proceedings

References in corpus (13)

• The pseudogap in high-temperature superconductors: an experimental survey
• Hidden Order in the Cuprates
• The doping dependence of T* - what is the real high-Tc phase diagram?
• On the superconductivity in the system with preformed pairs
• Predominantly Superconducting Origin of Large Energy Gaps in Underdoped Bi2Sr2CaCu2O8-d from Tunneling Spectroscopy
• Pairing Fluctuation Theory of Superconducting Properties in Underdoped to Overdoped Cuprates
• Bose-Einstein to BCS Crossover Picture for High-T_c Cuprates
• Pseudogap effects induced by resonant pair scattering
• Effects of carrier concentration on the superfluid density of high-T_c cuprates
• Superconducting transitions from the pseudogap state: d-wave symmetry, lattice, and low-dimensional effects
• On the Relationship Between the Pseudo- and Superconducting Gaps: Effects of Residual Pairing Correlations Below Tc
• Superconducting phase coherence in the presence of a pseudogap: Relation to specific heat, tunneling and vortex core spectroscopies
• Unusual thermodynamical and transport signatures of short coherence length superconductors: A BCS Bose-Einstein crossover approach

Cited by in corpus (4)

• Superfluid density in the underdoped YBa_2Cu_3O_{7-x}: Evidence for d-density wave order of pseudogap
• Quasiparticle spectrum of the cuprate BiSrCaCuO: Possible connection to the phase diagram
• Absence of a BCS-BEC crossover in the cuprate superconductors
• Pseudogap in the microwave response of YBa_2Cu_3O_{7-x}