spolarization

Spolarization is not a single standardized term, but is used in different contexts to refer to polarization phenomena, often as shorthand for spin polarization in condensed matter physics or as a variant spelling of polarization in optics. In general, polarization describes restricted orientations of a vector field: the electric field of light, electric dipoles in a material, or the spin angular momentum of particles.

Polarization of light: Light can be polarized linearly, circularly, or elliptically. Linear polarization occurs when the electric field oscillates in a single plane; circular polarization when the field rotates with constant magnitude; and elliptical polarization as the general case. Polarization is described by Stokes parameters and the Poincaré sphere. In anisotropic or magneto-optic media, polarization evolves due to birefringence, Faraday rotation, or dichroism. S-polarized and p-polarized light are terms used for the orientation of the electric field relative to the plane of incidence in reflection and transmission problems.

Spin polarization: In quantum systems, spin polarization refers to an imbalance in population between spin-up and spin-down states, quantified by P = (N↑ − N↓)/(N↑ + N↓). It is central to spintronics, where currents carry spin information. Spin polarization can be generated by optical orientation (using circularly polarized light), via spin injection from ferromagnetic contacts, or by strong spin-orbit coupling. It is measured by techniques such as magneto-optical Kerr effect, Andreev reflection, or transport in spin-valve structures.