Effects of heavy ion irradiation on the magnetic anomaly in Bi₂Sr₂CaCu₂O_8+y crystals near transition temperature

Abstract

We report the observation of an anomalous magnetization behavior in single crystal of Bi₂Sr₂CaCu₂O_8+y near the transition temperature after 200 MeV Ag ion irradiation with a fluence of 2.5 × 10¹¹ ions/cm². We argue that the magnetization anomaly (the virgin curve lying above the return leg and the presence of a characteristic crossover temperature, T∗) is the manifestation of fluctuation phenomena as were observed in as-grown crystal. The columnar defects produced by the heavy ions could not reduce the anisotropy and enhance the interlayer coupling to such an extent that the fluctuation effects near the transition temperature region were suppressed.