Flux dynamics and vortex phase diagram of the new superconductor $MgB_2$

H. H. Wen; S. L. Li; Z. W. Zhao; Y. M. Ni; Z. A. Ren; G. C. Che; Z. X. Zhao

doi:10.1016/S0921-4534(01)00936-4

paper

Flux dynamics and vortex phase diagram of the new superconductor $M g B_{2}$

arXiv:cond-mat/0103521 · doi:10.1016/S0921-4534(01)00936-4

Abstract

Magnetic critical current density and relaxation rate have been measured on $M g B_{2}$ bulks from 1.6 K to $T_{c}$ at magnetic fields up to 8 Tesla. A vortex phase diagram is depicted based on these measurement. Two phase boundaries $H_{i r r}^{b u l k} (T)$ and $H_{i r r}^{g} (T)$ characterizing different irreversible flux motions are found. The $H_{i r r}^{b u l k} (T)$ is characterized by the appearance of the linear resistivity and is attributed to quantum vortex melting induced by quantum fluctuation of vortices in the rather clean system. The second boundary $H_{i r r}^{g} (T)$ reflects the irreversible flux motion in some local regions due to either very strong pinning or the surface barrier on the tiny grains.

4 pages, 5 figures

Flux dynamics and vortex phase diagram of the new superconductor MgB2​

Abstract

Flux dynamics and vortex phase diagram of the new superconductor $M g B_{2}$