PINNING
*
In real samples – material imperfections pin vortices
*
*
*
*
*
*
Critical current density
J
c
*
F
L
=J
c
x
F
o
= F
p
*
*
J<J
c
pinned
z
no dissipation
*
*
J<J
c
pinned
z
moving vortices
z
voltage drop
*
*
Pinning center=
hole, impurity,
Y=0
F
p
Pinning Force per unit length