Origin of magnetic flux-jumps in Nb films subject to mechanical vibrations and corresponding magnetic perturbations

Article

关键词: SELF-ORGANIZED CRITICALITY;    SUPERCONDUCTING MGB2 FILMS;    THIN-FILMS;    VORTEX AVALANCHES;    II SUPERCONDUCTORS;    INSTABILITY;    PENETRATION;    PEAK;    RELAXATION;    VORTICES;   

DOI  :  10.1103/PhysRevB.97.014524

来源: SCIE

【 摘 要 】

In this paper the origin of flux-jumps in Nb thin films is established during magnetization measurements using a vibrating sample magnetometer (VSM). Magnetization measurements of the flux avalanche activity show its strong dependence on frequency and amplitude of VSM vibration. In particular, under certain conditions the vibrations induce a transition from a stable superconducting critical state to an undercritical state, accompanied by the 20-fold drop in the magnetic moment. These features allow the elucidation of the origin of the flux-jumps. In contrast to the commonly assumed thermomagnetic instabilities to be responsible for the flux-jumps in Nb films, our results provide solid support for an alternative explanation being due to criticality-built instability well represented by a sandpile. Considering properties of the flux-flow during a flux avalanche regime allows us to estimate nonuniformity of a magnetic field in a VSM sample space developed as a result of vibrations.

【 授权许可】

Free