Vortex dynamics in Co-doped and K-doped BaFe$_{2}$As$_{2}$ with point defects

The discovery of iron-based superconductors urges scientists and engineers to study not only superconducting mechanism but also possible applications. In view of this situation, it is important to study vortex dynamics for understanding fundamental properties as well as for suggesting a suitable fabrication process in this system. In particular, the interaction between vortices and defects attract tremendous attention, which is because this interaction is responsible for finite critical current density $J_c$. The interaction changes with dimensionality and morphology of defects. In cuprate superconductors, vortex manifold shows vortex glass phase with point defects and Bose glass phase with columnar defects. Besides, in both cases, $J_c$ shows pronounced enhancement compared with that in a pristine sample. We have already reported the enhancement of $J_c$ by the introduction of point or columnar defects in the case of Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$ crystal. In this talk, we show the results in proton-irradiated BaFe$_2$As$_2$ with electron- or hole-doping. The quantitative analysis reveals the doubling of pinning potential without changing the glassy exponent in Co-doped compounds, in addition to 2.5 times enhancement of $J_c$. Similar effects are observed in K-doped crystals.