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Chapter 8
Another Superconductors
At contact with the d-shell electron, a freely moving electron induces onto it the
magnetic field of the order of value:
H ≈ e v
rc
2 c . (8.2)
The magnetic moment of d-electron is approximately equal to the Bohr magneton.
Therefore the energy of the magnetic interaction between a moving electron of
conductivity and a d-electron is approximately equal to:
E µ ≈ e2
2r c
v
c . (8.3)
This energy is not connected with the process of destruction of superconductivity.
Whereas, in metals with a filled d-shell (type-I superconductors), the whole heating
energy increases the kinetic energy of the conductivity electrons and only a small part of
the heating energy is spent on it in transition metals:
E k
E µ + E k
≃ mv t
h a B. (8.4)
So approximately
E k
E µ + E k
≃ a B
L 0
. (8.5)
Therefore, whereas the dependence of the gap in type-I superconductors from the heat
capacity is defined by Eq.(7.3), it is necessary to take into account the relation Eq.(8.5) in
type-II superconductors for the determination of this gap dependence. As a result of this
estimation, we can obtain:
∆ 0 ≃ Θγ 2 (
where 1/2 is the fitting parameter.
)
Ek
E µ + E k
≃ Θγ 2 (
aB
L 0
) 1
2 , (8.6)
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