摘要
The nature of resistive transition of high-quality crystalline thin films of YBa2Cu3O7-δhas been studied under magnetic fields（H） applied along the c direction over a wide range of doped holes, p, in the Cu O2 planes. The field- and temperature-dependent in-plane resistivity, ρab（T, H）, has been analyzed within the thermally assisted flux-flow（TAFF）formalism. The flux activation energy, U（T, H）, has been extracted from this analysis. The low-T part of the ρab（T, H）data can be described by an activation energy having the functional form of U（T, H） =（1- t）m（H-0/H）β, where t = T /Tc（reduced temperature）, and H0 is a field scale that primarily determines the magnitude of U（T, H）. The temperature exponent, m, shows a systematic variation with p, whereas the field exponent, β, is insensitive to the p values and is close to unity. The H0, on the other hand, changes rapidly as p is varied. U（T, H） is linked to the pinning potential and consequently on the superconducting condensation energy. Since the normal state pseudogap directly affects superconducting condensation energy, a clear correspondence between H0 and the PG energy scale, ε g, is found. Possible implications of these results are discussed.
The nature of resistive transition of high-quality crystalline thin films of YBa2Cu3O7-δhas been studied under magnetic fields（H） applied along the c direction over a wide range of doped holes, p, in the Cu O2 planes. The field- and temperature-dependent in-plane resistivity, ρab（T, H）, has been analyzed within the thermally assisted flux-flow（TAFF）formalism. The flux activation energy, U（T, H）, has been extracted from this analysis. The low-T part of the ρab（T, H）data can be described by an activation energy having the functional form of U（T, H） =（1- t）m（H-0/H）β, where t = T /Tc（reduced temperature）, and H0 is a field scale that primarily determines the magnitude of U（T, H）. The temperature exponent, m, shows a systematic variation with p, whereas the field exponent, β, is insensitive to the p values and is close to unity. The H0, on the other hand, changes rapidly as p is varied. U（T, H） is linked to the pinning potential and consequently on the superconducting condensation energy. Since the normal state pseudogap directly affects superconducting condensation energy, a clear correspondence between H0 and the PG energy scale, ε g, is found. Possible implications of these results are discussed.
基金
the Mac Diarmid Institute for Advanced Materials and Nanotechnology, New Zealand, and the IRC in Superconductivity, University of Cambridge, UK, for funding this research
