Dynamics of stripe patterns in type-I superconductors subject to a rotating field

The evolution of stripe patterns in type-I superconductors subject to a rotating in-plane magnetic field is investigated magneto-optically. The experimental results reveal a very rich and interesting behavior of the patterns. For small rotation angles, a small parallel displacement of the main part of the stripes and a corotation of their very ends are observed. For larger angles, small sideward protrusions develop, which then generate a zigzag instability, ultimately leading to a breaking of stripes into smaller segments. The short segments then start to corotate with the applied field although they lag behind by approximately 10 degrees. Very interestingly, if the rotation is continued, reconnection of segments into longer stripes also takes place. These observations demonstrate the importance of pinning in type-I superconductors.