Imaging Flux Avalanches in V$_3$Si Superconducting Thin Films

When developing superconducting devices patterned on thin films, one should bear in mind that flux avalanches might occur for some materials at a certain window of applied fields and temperatures. Although the A15 superconductors are well known and used in a variety of purposes, there are no studies about flux avalanches in V 3 Si thin films. In the present work, we report the observation of flux avalanches in films of V 3 Si, grown by pulsed laser deposition on a LaAlO 3 substrate. The range of temperatures and applied magnetic fields at which the avalanches take place is determined using dc-magnetometry. Magneto-Optical Imaging is employed to visualize the occurrence and spatial distribution of such flux avalanches. Images of the flux penetrated into the samples indicate a clear anisotropic distribution, which is ascribed to a thickness gradient. The observation of flux avalanches reported here implies that attention to this feature must be given when films of V 3 Si are envisaged for possible applications.