Observation of Vortex Lattice Related Anomalies in Polycrystalline YBa&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;Cu&amp;lt;sub&amp;gt;3&amp;lt;/sub&amp;gt;O&amp;lt;sub&amp;gt;7-x&amp;lt;/sub&amp;gt; Near the Superconducting Transition

S B Ota

doi:10.4236/jmp.2012.310183

Abstract

The d.c. I-V characteristic of polycrystalline YBa2Cu3O7-x high temperature superconductors (HTSC) is measured near the transition temperature (Tc). The Tc was found to be 90 K with a width of 2 K. The voltage was measured at various current values and with reversing the current. A difference in voltage was found for forward and reverse current directions near Tc. The observed directionality of the I-V characteristic can be understood in terms of quantized magnetic flux by the self-field of the current and the proximity junctions in these materials. This can also be understood qualitatively as due to the d-wave superconductivity. The measured dc voltage showed increased noise near Tc which is possibly related to 1/f noise due to the motion of Abrikosov flux lines.

Highlights

Superconducting materials have attracted interest in recent years [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17]
The effect of magnetic field on the specific heat anomaly near the superconducting transition is considerably different from the effect on conventional superconductors
This is unlike the type-II conventional superconductors in which case the application of magnetic field shifts the specific heat jump at Tc to lower temperatures with practically very little change in the shape of the anomaly

Summary

Introduction

Superconducting materials have attracted interest in recent years [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17]. The d.c. I-V characteristic of polycrystalline YBa2Cu3O7−x high temperature superconductors (HTSC) is measured near the transition temperature (Tc). The voltage was measured at various current values and with reversing the current. A difference in voltage was found for forward and reverse current directions near Tc. The observed directionality of the I-V characteristic can be understood in terms of quantized magnetic flux by the self-field of the current and the proximity junctions in these materials.

Results

Conclusion