3D XY and lowest Landau level fluctuations in deoxygenated YBCO thin films

Abstract

Conductivity measurements reflect vortex solid melting in YBCO films. Field-independent glass exponents nu_g=1.9 and z_g=4.0 describe the transition T_g(H) for 0<H<26 T. At low fields, 3D XY exponents nu_{XY}=0.63 and z_{XY}=1.25 are also observed, with z_{XY} smaller than expected. These compete with glass scaling according to multicritical theory. A predicted power-law form of T_g(H) is observed for 0.5T_c<T_g<T_c. For T_g<0.5T_c, 3D XY scaling fails, but a lowest Landau level analysis becomes possible, obtaining T_{c2}(H) with positive curvature.

4 pages, 5 .eps figures, To be published in Phys. Rev. Lett

References in corpus (2)

• Scaling in high-temperature superconductors
• Low-Magnetic Field Critical Behavior in Strongly Type-II Superconductors

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