1/3/2004
6
•
X
BASICS: SURFACE ENERGY
Gap-
D
Ground state
Excited states
Thermodynamic Critical field
Two types of superconductors:
Type I
x>l
F
i
>0 always
Coherence
length
Surface energy of
interface:
F
i
=(
H
c
2
x -
H
2
l)
/ 8
p
H(x)
l(T)