SWIFT HEAVY-ION IRRADIATION EFFECTS ON THE SUPER-CONDUCTING MATERIAL LA1.65SR0.15CUO4

The effects of columnar defects produced by swift heavy-ion irradiatio n on magnetic flux pinning were studied for the polycrystalline La1.85 Sr0.15CuO4. The bulk specimens were irradiated with 3.5GeV Xe-136(31+) ions from a single direction or multi-directions in order to investig ate the effects of columnar defect configuration. The magnetization hy steresis was measured with a super-conducting quantum interference dev ice (SQUID) magnetometer, and the critical current density J(c) and ir reversibility line were observed. In the specimens irradiated from mul ti-directions, more enhancement of the critical current density and la rger shifts of the irreversibility line to higher fields were observed than in the specimens irradiated from a single direction.