Vortex pinning in an irradiated Bi-2212 single crystal: What about the screening of the transverse magnetic field?

Abstract

Magneto-transport measurements I-V have been recorded for B=300G at both low and high temperature in Bi-2212 single crystals irradiated along the c-axis. Pinning properties have been studied versus the temperature T, and the angle Θ between B and the columnar defects (CD's). We show that Ic decreases as t=T/T c is lowered below 0.3. This result suggests that the rigidity of the moving vortex system increases as T decreases. The angular dependence of I c confirms that, at low temperature, the pinning is collective as it has already been shown. More, the fact that the vortex penetration always take place parallel to the c-axis of the sample evidences an intrinsic infinite tilt modulus C44. At high temperature, C44 is finite and the localization of the discrete vortices takes place over different column sites.