Correlated vortex pinning in Si-nanoparticle doped MgB2

I. Kusevic; E. Babic; O. Husnjak; S. Soltanian; X. L. Wang; S. X. Dou

doi:10.1016/j.ssc.2004.09.035

paper

Correlated vortex pinning in Si-nanoparticle doped MgB2

arXiv:cond-mat/0311425 · doi:10.1016/j.ssc.2004.09.035

Abstract

The magnetoresistivity and critical current density of well characterized Si-nanoparticle doped and undoped Cu-sheathed MgB $_{2}$ tapes have been measured at temperatures $T \geq 28$ K in magnetic fields $B \leq 0.9$ T. The irreversibility line $B_{i r r} (T)$ for doped tape shows a stepwise variation with a kink around 0.3 T. Such $B_{i r r} (T)$ variation is typical for high-temperature superconductors with columnar defects (a kink occurs near the matching field ) and is very different from a smooth $B_{i r r} (T)$ variation in undoped MgB $_{2}$ samples. The microstructure studies of nanoparticle doped MgB $_{2}$ samples show uniformly dispersed nanoprecipitates, which probably act as a correlated disorder. The observed difference between the field variations of the critical current density and pinning force density of the doped and undoped tape supports the above findings.

4 pages, 4 figures