Xinsheng Sean Ling, Brown University, DMR 0406626Peak Effect in Polycrystalline Vortex Matter

Goal: We were motivated by the question of why some type-II superconductors exhibit a peak effect anomaly in critical current. The project will provide new understanding of type-II superconductors and their ability in carrying electricity.

Sample: V-Ti alloy

Experimental methods: small-angle neutron scattering (SANS)and ac magnetic susceptibility

Results: V-Ti alloy is a well-known type-II superconductor which is strongly disordered (see SEM micrograph in inset) yet it also exhibits a peak effect (left panel) at strongmagnetic fields. Our SANS experiments (top images) proved that this peak effect arises from a polycrystalline vortex matter.

I. K. Dimitrov, N. D. Daniilidis, C. Elbaum, J.W. Lynn, and X. S. Ling, Phys. Rev. Lett. 99, 047001 (2007).

Education

The project provided educational opportunities to Ivo Dimitrov and Nikos Daniilidis.Here the PI is congratulating them both for successfully completing their Ph.D. degrees.

Ivo Dimitrov, Ph.D.’07Nikolaos Daniilidis, Ph.D.’08

Xinsheng Sean Ling, Brown University, DMR 0406626