Huge magnetostriction in superconducting single-crystalline BaFe1.908Ni0.092As2

The performance of iron-based superconductors in high magnetic fields plays an important role for their practical application. In this work, we measured the magnetostriction and magnetization of BaFe1.908Ni0.092As2 single crystals using pulsed magnetic fields up to 60 T and static magnetic fields up to 33 T, respectively. A huge longitudinal magnetostriction (of the order of 10(-4)) was observed in the direction of twin boundaries. The magnetization measurements evidence a high critical-current density due to strong bulk pinning. By using magnetization data with an exponential flux-pinning model, we can reproduce the magnetostriction curves qualitatively. This result shows that the magnetostriction of BaFe1.908Ni0.092As2 can be well explained by a flux-pinning-induced mechanism.