Harvard Condensed Matter Theory Seminars

Zlatko Tesanovic, Johns Hopkins

Emergence of Cooper pairs and the phase diagram of cuprates

I discuss an effective theory for the charge 2e sector of underdoped cuprates, based on the microscopic physics of a correlated, quantum disordered d-wave superconductor. The theory describes a superconductor giving way at low doping (x < x_c) to a ground state with quantum vortex-antivortex fluctuations and enhanced diamagnetism, but no true superconducting (off-diagonal) order. At extreme underdoping (x << x_c), the Copper pairs ``disintegrate'', as charge 2e ``detaches'' from spin-singlet bonds -- the ensuing ground state is governed by antiferromagnetic (diagonal) rather than by superconducting (off-diagonal) correlations. Various features of the theory are evaluated in light of recent experiments and are used to draw general conclusions about the phase diagram.

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