Diamagnetism and Cooper Pairing Above T-c in Cuprates
In the cuprate superconductors, Nernst and torque magnetization experiments have provided evidence that the disappearance of the Meissner effect at T{sub c} is caused by the loss of long-range phase coherence, rather than the vanishing of the pair condensate. Here we report a series of torque magnetization measurements on single crystals of La{sub 2-x}Sr{sub x}CuO{sub 4} (LSCO), Bi{sub 2}Sr{sub 2-y}La{sub y}CuO{sub 6} (Bi 2201), Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}}, and optimal YBa{sub 2}Cu{sub 3}O{sub 7}. Some of the measurements were taken to fields as high as 45 T. Focusing on the magnetization above T{sub c}, we show that the diamagnetic term M{sub d} appears at an onset temperature T{sub onset}{sup M} high above T{sub c}. We construct the phase diagram of both LSCO and Bi 2201 and show that T{sub onset}{sup M} agrees with the onset temperature of the vortex Nernst signal T{sub onset}{sup v}. Our results provide thermodynamic evidence against a recent proposal that the high-temperature Nernst signal in LSCO arises from a quasiparticle contribution in a charge-ordered state.
- Research Organization:
- Brookhaven National Lab. (BNL), Upton, NY (United States)
- Sponsoring Organization:
- USDOE SC OFFICE OF SCIENCE (SC)
- DOE Contract Number:
- DE-AC02-98CH10886
- OSTI ID:
- 1040398
- Report Number(s):
- BNL-90231-2010-JA; R&D Project: PO-010; KC0202010; TRN: US1202424
- Journal Information:
- Physical Review. B, Condensed Matter and Materials Physics, Vol. 81, Issue 5; ISSN 1098-0121
- Country of Publication:
- United States
- Language:
- English
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