Effects of Heavy-Ion Irradiation on the Superconducting Properties of Ba(Fe1-xCox)2As2 Single Crystals

Since their discovery in 2008, the development of ironbased superconducting materials has been undertaken because of their high critical field, relatively high critical temperature and metal like behavior, that make these materials promising for a number of applications, including magnets and cables. Iron-based superconductors have received a great deal of attention also from the fundamental point of view, due to the coexistence of superconductivity and magnetism in the same system. Within this framework, the ability to induce controlled defects into the material is of chief importance to study its properties depending on disorder, and a well assessed method for this task is particle irradiation. We focused our attention on the effects of heavy ion irradiation on the properties of Ba(Fe0.93Co0.07)2As2 single crystals (Ba(Fe,Co)As henceforth), prepared by the FeAs/CoAs self flux method [1] at the Department of Applied Physics, The University of Tokyo, Japan. In particular, we studied the possibility of tailoring the vortex pinning properties in order to achieve improvement of critical current density, Jc, that is a challenge in view of high power applications. In this Report we describe main results concerning enhancement and anisotropy of vortex pinning induced by 250 MeV Au-ion irradiations at the LNL Tandem accelerator. Beside the positive effects of moderate-fluence irradiations on Jc, the radiation hardness of the material has been checked by means of irradiations to higher fluences (up to 1.61011 cm-2) and compared to radiation hardness of cuprate high-Tc superconductors.