Original scientific paper
Ground state superconducting phase fluctuations as a precursor for strong critical fluctuations in high-Tc superconductors
J. R. Cooper
; Interdisciplinary Research Centre in Superconductivity, University of Cambridge, Madingley Road, Cambridge CB3 0HE, United Kingdom
D. Babić
; Institute of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland; Department of Physics, Faculty of Science, University of Zagreb, Bijenička 32, HR-10001 Zagreb, Croatia
J. W. Loram
; Interdisciplinary Research Centre in Superconductivity, University of Cambridge, Madingley Road, Cambridge CB3 0HE, United Kingdom
Wai Lo
; Interdisciplinary Research Centre in Superconductivity, University of Cambridge, Madingley Road, Cambridge CB3 0HE, United Kingdom; Texas Center for Superconductivity, University of Houston, Houston,U.S.A.
D. A. Cardwell
; Interdisciplinary Research Centre in Superconductivity, University of Cambridge, Madingley Road, Cambridge CB3 0HE, United Kingdom
Abstract
We analyse the reversible magnetisation and heat capacity of YBa2Cu3O7−δ in the “vortex liquid” state and find that both properties are reasonably well described by the 3D XY critical-fluctuation model. The free-energy density in the “vortex liquid” state has a particularly simple form over a wide range of fields (H) and temperatures (T). This leads us to a picture in which the presence of critical fluctuations in high-Tc superconductors is directly linked to the remarkably small number of overlapping Cooper pairs at T=0 and H=0 rather than low dimensionality or high temperatures.
Keywords
high-Tc materials; magnetisation; heat capacity; critical fluctuations
Hrčak ID:
301025
URI
Publication date:
3.10.1999.
Visits: 221 *