Dependence of the vortex-solid phase transition of YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} thin films on anisotropy: Evidence for a universal phase boundary
- Physics Department, Purdue University, West Lafayette, Indiana 47907 (United States)
- Argonne National Laboratory, Materials Science Division, Argonne, Illinois 60439 (United States)
The vortex-solid phase boundary of YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} (YBCO) thin films was studied as a function of oxygen stoichiometry, {delta}, using magnetotransport measurements. Experimental evidence for a characteristic crossover field, H{sub 0}, separating two distinct types of behavior, was observed for films with {delta}{gt}0.12 to occur at a temperature, T{sub 0}, that is about half of the superconducting transition temperature (T{sub 0}{approx}T{sub c}/2). When plotted as H{sub g}(T)/H{sub 0} versus (1{minus}T/T{sub c}), all of the boundaries collapse onto a single universal curve. An implication of this collapse is that an empirical equation which depends only on T{sub c}, the anisotropy {gamma}, and T{sub 0}, H{sub g}(T)=H{sub 0}[(1{minus}T/T{sub c})/(1{minus}T{sub 0}/T{sub c})]{sup n}, where H{sub 0}=[1.2{phi}{sub 0}/(s{gamma}){sup 2}], can be used to describe the H{sub g}(T) boundary for any YBCO thin film and other disordered YBCO materials. Estimates of the vortex-glass (VG) correlation length, {xi}{sub VG}, are made. The value of {xi}{sub VG} at the point where VG scaling finally breaks down is found to be independent of magnetic field for the fully oxygenated films, however, it is dependent on field for deoxygenated films. This result suggests that the pinning in the fully oxygenated films is dominated by correlated disorder while pinning in the deoxygenated films becomes dominated by quenched disorder. {copyright} {ital 1997} {ital The American Physical Society}
- Research Organization:
- Purdue Univ., West Lafayette, IN (United States)
- DOE Contract Number:
- FG02-90ER45427
- OSTI ID:
- 496748
- Journal Information:
- Physical Review, B: Condensed Matter, Vol. 55, Issue 17; Other Information: PBD: May 1997
- Country of Publication:
- United States
- Language:
- English
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