Electron scattering dependence of dendritic magnetic instability in superconducting MgB2 films

We studied magnetic stability in both ultra-pure and carbon-doped MgB$_{2}$ films using magneto-optical imaging, transport and bulk magnetization measurements. In the carbon-doped MgB$_{2}$ film, dendritic flux-jumps were observed at low temperature as reported in previous experiments. However, a remarkably stable flux penetration was observed in the ultra-pure MgB$_{2}$ film, clearly showing the classic behavior of the critical state model. Such different behaviors indicate that the electron scattering ultimately controls the magnetic stability of MgB$_{2}$ films.