Paramagnetism

Paramagnetism is a form of magnetism in which unpaired magnetic moments align partly with an applied magnetic field, producing weak attraction that disappears when the field is removed.

Magnetic moment: A vector measure of the strength and orientation of a system’s magnetic source. Unpaired electrons supply the moments that align with an applied field.
Electron spin: An intrinsic quantum angular momentum carried by electrons. Electron spin contributes to the magnetic moments responsible for paramagnetism.
Diamagnetism: A form of magnetism in which an applied field induces a moment opposing the field. Unlike paramagnetism, it produces weak repulsion and occurs in all materials.
Electron paramagnetic resonance: A spectroscopy technique that detects transitions between electron-spin energy levels in a magnetic field. It measures unpaired electrons in paramagnetic atoms, molecules, and defects.
Zeeman effect: The splitting of atomic or molecular energy levels in an external magnetic field. Field-induced energy shifts favor magnetic moment orientations aligned with the field.
Orbital angular momentum: The quantum angular momentum associated with a particle’s spatial motion around a center. Unquenched orbital motion can add to an atom’s magnetic moment.
Ferromagnetism: A form of magnetism in which interactions align moments into domains that can retain magnetization. Its collective alignment can persist after the applied field is removed.
Magnetic separation: A process that separates materials according to their responses to a magnetic field. Strong-field gradients can separate weakly paramagnetic substances from other materials.
Langevin theory of paramagnetism: A classical model describing the magnetization of noninteracting magnetic moments in a field. It predicts partial alignment and the decrease of magnetization as temperature rises.
Hund's rules: Rules that predict how electrons occupy orbitals to minimize an atom’s energy. They help determine the number of unpaired electrons in an atom or ion.

Linked from 24 pages