Type 1 superconductors usually consist of pure metals;
elemental metals and not alloys. These ones will create the
property of zero electrical resistance and diamagnetism below the
critical cooling temperature. Diamagnetism, as explained before,
is the reaction magnetic field created by the pure metal in
opposition to an applied magnetic field.
Type 2 superconductors will act very similarly as type 1
superconductors, except diamagnetism will act differently. Type 2
superconductors will enter the superconducting phase at a
particular critical temperature just like type 1 superconductors,
except as the temperature is further decreased, the material will
enter a semi-superconducting phase where there are regions of the
material that are not changed. As the temperature is further
increased, it soon returns to the superconducting phase.
This is one way to determine the type of superconductor. The best
way to determine what type of superconductor the material is is by
applying a magnetic field to the superconductor. For both types of
superconductors, applying a magnetic field will cause an
expulsion, as expected. For a type 1 superconductor, increasing
the applied magnetic field will linearly increase the explusion
created by the superconductor. For a type 2 superconductor, the
relationship between the applied magnetic field and explusion will
be the same; however at a particular value (called the critical
field), the expulsion will break down and enter the vortex region
where the expulsion is chaotic and unstable. Just like the
temperature, the type 2 superconductor will enter the normal
superconducting phase if enough of a magnetic field is applied.
The pattern of these two types of superconductor under increasing
an applied magnetic field can be visualized by the graph shown
below:
