| Summary: | Paramagnetism describes a type of magnetism whereby a material is weakly attracted by an external magnetic field. The material forms induced magnetic fields in the direction of the external magnetic field. Pauli-paramagnetism is a weak form of paramagnetism. It arises in a conductor when a magnetic field is applied and its conduction band is split into a spin-up and a spin-down band due to the differences in magnetic potential energy for spin-up and spin-down electrons. As the Fermi level must be the same for each band, there is inevitably a surplus of the type of spin in the band that shifted downwards. In a regular (non-Pauli paramagnetic) superconductor, the superconductivity is destroyed due to the orbital supercurrents. However, in a Pauli-paramagnetic superconductor, the normal state is induced by the coupling of the magnetic field to the spin of the electrons (i.e. in materials with significant Pauli paramagnetism). The effects of the Pauliparamagnetism are visible in the magnetic vortices of the superconductor as this is where the electron pairs have been “broken up”, and the nature of these vortices can be probed by small-angle neutron scattering.
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