Shift of the surface-barrier part of the irreversibility line due to columnar defects in Bi2Sr2CaCu2O8 thin films

Abstract In the present work we report the results of studying the influence of the uranium-ion irradiation of the Bi 2 Sr 2 CaCu 2 O 8 thin films on the high-temperature part (close to T c ) 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, B Φ >1 T. This fact is in good agreement with the theoretical prediction by Koshelev and Vinokur of suppression of surface-barrier by columnar defects.