Measurement of vortex motion in a type-II superconductor: A novel use of the neutron spin-echo technique
We have used the neutron spin-echo technique to measure the small energy change of neutrons which are diffracted by a moving vortex lattice in a low-pinning Nb-Ta superconducting sample. A transport current was passed in the mixed state to cause flux line movement. In the case of uniform motion, the flux velocity v(L) was given as expected by the values of electric and magnetic fields, via E = -v(L)wedgeB. We show that with a nonuniformly moving vortex lattice, one can measure the dispersion of the velocities, opening up new possibilities for investigating moving vortex lines.
Forgan
EM
School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT United Kingdom.
Kealey
PG
Johnson
ST
Pautrat
A
Simon
C
Lee
SL
Aegerter
CM
Cubitt
R
Farago
B
Schleger
P