Oxygen displacement in a ¹⁰⁷Ag¹⁷⁺ ion irradiated Bi₂Sr₂CaCu₂O₈ single crystal

Abstract

We have studied the magnetic field (H∥c) dependent rf dissipation (H_rf∥a) in an as-grown Bi₂Sr₂CaCu₂O₈ single crystal prior to and after irradiation with 250 MeV ¹⁰⁷Ag¹⁷⁺ ions. In a comparison of the responses from the as-grown crystal with an air-annealed crystal, features due to oxygen deficient regions acting as weak links in the former are identified. These features disappear immediately after irradiation of the as-grown crystal. We attribute such behavior to the displacement of oxygen from columnar tracks to deficient regions thus eliminating the weak links. Losses from the same irradiated as-grown crystal stored at 300 K for 60 days show that the features similar but not identical to those observed in the pristine state have reappeared implying that the displaced oxygen is in a metastable configuration in the deficient regions and hence is mobile due to thermal effects even at 300 K.