Isothermal current-voltage (J-E) characteristics have been measured for films of lead (Pb)-indium (In) alloys, Pb100-xInx (x=8.23, 4.0 and 2.0 wt.%) in the mixed state. The isothermal logJ vs. logE curves similar to those characterizing the vortex glass-vortex liquid (VL) transition in copper oxide superconductors have been observed, though the reversibility of magnetization curve for bulk samples in the mixed state could not be detected within the experimental accuracy in the present study. Using Fisher's theoretical relations, the transition temperature Tg(H), the static and dynamical critical exponents are determined. The variation of the exponents with H in low magnetic fields reported in high temperature superconductors was not observed. The upper critical magnetic field Hc2(T) determined by resistivity vs. temperature in the mixed state increases with increasing In concentration, but the Tg(H) is almost independent of the In concentration. A region between Hc2(T) and Tg(H) in a plane of H and T, which may be considered as the VL region, becomes wider with increasing In concentration.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Energy Engineering and Power Technology
- Electrical and Electronic Engineering