Dendritic flux instability in MgB2 films above liquid hydrogen temperature

Magnetic flux instability limits potential applications of superconductors such as MgB2 in practical devices. Previous studies in MgB2 films exposed to magnetic fields revealed the occurrence of dendritic flux avalanches at temperatures below T similar to 10 K. In the present work it is shown that films of MgB2 exposed to a fast-ramped magnetic field display a dendritic flux instability at elevated temperatures, up to 23 K. Such instability can therefore cause malfunctioning of practical devices based on MgB2 films even when operating at liquid hydrogen temperature.