Critical Magnetic Field |
|
| The superconducting state cannot exist in the presence of a magnetic field greater than a critical value, even at absolute zero. This critical magnetic field is strongly correlated with the critical temperature for the superconductor, which is in turn correlated with the bandgap. Type II superconductors show two critical magnetic field values, one at the onset of a mixed superconducting and normal state and one where superconductivity ceases. | |
| The dependence of the critical magnetic field upon temperature is of the approximate form | |
Bc(T) = Bc(0)(1 - (T/Tc)2) |
|
| which shows that a magnetic field works against superconductivity. | |
| The Type II superconductors have much higher critical magnetic fields than Type I, but for most of that field range they are mixtures of normal and superconducting. | |
|