Shift of the surface-barrier part of the irreversibility line due to columnar defects in Bi_2Sr_2CaCu_2O_8 thin films

TL;DR

This study investigates how uranium-ion irradiation affects the irreversibility line in Bi_2Sr_2CaCu_2O_8 thin films, showing a shift towards lower temperatures and fields, especially at high irradiation doses.

Contribution

It provides experimental evidence that columnar defects from irradiation suppress the surface barrier, confirming theoretical predictions.

Findings

Irreversibility line shifts to lower temperatures and magnetic fields after irradiation.

Larger irradiation doses (>1T) cause more significant shifts.

Results agree with theoretical models by Koshelev and Vinokur.

Abstract

We report the results of studying the influence of the uranium-ion irradiation of the Bi_2Sr_2CaCu_2O_8 thin films on the high-temperature part (close to critical temperature) of their irreversibility line. We studied irreversible properties of the films by measuring the hysteresis of nonresonant microwave absorption. The results have revealed the shift of irreversibility line towards low temperatures and magnetic fields. The effect is most significant for the films irradiated with large doses, more than 1T. This fact is in good agreement with the theoretical prediction by Koshelev and Vinokur of suppression of surface barrier by columnar defects.