d-wave duality and its reflections in high-temperature superconductors

Abstract

The Bardeen–Cooper–Schrieffer theory describes the formation of electron pairs, or Cooper pairs, and their instant condensation into a superconducting state. Helium atoms are ‘preformed’ bosons and, in addition to their superfluid state, can also form a quantum solid that lacks phase coherence. Here I show that the fate of Cooper pairs can be more varied than the Bardeen–Cooper–Schrieffer or helium paradigms. In copper oxide d-wave superconductors, Cooper pairs are non-local objects, with both centre-of-mass and relative motions. As the level of doping of charge carriers decreases, the centre-of-mass fluctuations force a correlated d-wave superconductor into a state with enhanced diamagnetism and robust but short-ranged superconducting order. At extreme underdoping, the relative fluctuations take over and two pseudogaps—‘small’ (charge) and ‘large’ (spin)—emerge naturally, as Cooper pairs ‘disintegrate’ and charge detaches from spin-singlet bonds. The ensuing ground state(s) are governed by antiferromagnetic rather than by superconducting correlations. There are two major theories regarding the normal state of a high-temperature superconductor: that the ‘pseudogap’ state is either a disordered superconductor or a distinct and competing phase. But could it be both?

Cite this article

Tešanović, Z. d-wave duality and its reflections in high-temperature superconductors. Nature Phys 4, 408–414 (2008). https://doi.org/10.1038/nphys910

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