Critical current densities and flux creep rate in Co-doped BaFe2As2 with columnar defects introduced by heavy-Ion irradiation

Abstract

We report the formation of columnar defects in Co-doped BaFe2As2 single crystals with different heavy-ion irradiations. The formation of columnar defects by 200MeV Au ion irradiation is confirmed by transmission electron microscopy and their density is about 40% of the irradiation dose. Magneto-optical imaging and bulk magnetization measurements reveal that the critical current density Jc is enhanced in the 200MeV Au and 800MeV Xe ion irradiated samples while Jc is unchanged in the 200MeV Ni ion irradiated sample. We also find that vortex creep rates are strongly suppressed by the columnar defects. We compare the effect of heavy-ion irradiation into Co-doped BaFe2As2 and cuprate superconductors.