Type I & II Superconductors
The classification of superconductors based on their magnetic field response and flux penetration characteristics.
Governing formula
Type I: Single H_c; Type II: Lower H_c1 and Upper H_c2
SI unit
T or A/m (Critical Magnetic Field)
In depth
Type I superconductors abruptly lose superconductivity at a single critical magnetic field H_c via complete Meissner expulsion. Type II superconductors feature an intermediate 'vortex state' between H_c1 and H_c2 where quantized magnetic flux tubes penetrate, allowing them to remain superconducting in intense magnetic fields.
Examples in the real world
Type I elemental lead vs Type II Nb₃Sn wires used in high-field 15 Tesla superconducting magnets.