In physics, mainly quantum mechanics and particle physics, a spin magnetic moment is the magnetic moment induced by the spin of elementary particles. For example the electron is an elementary spin-1/2 fermion. Quantum electrodynamics gives the most accurate prediction of the anomalous magnetic moment of the electron.
"Spin" is a non–classical property of elementary particles, since classically the "spin angular momentum" of a material object is really just the total orbital angular momenta of the object's constituents about the rotation axis. Elementary particles are conceived as points, which have no axis to "spin" around.
In general, a magnetic moment can be defined in terms of an electric current and the area enclosed by the current loop. Since angular momentum corresponds to rotational motion, the magnetic moment can be related to the orbital angular momentum of the charge carriers in the constituting the current. However, in magnetic materials, the atomic and molecular dipoles have magnetic moments not just because of their quantized orbital angular momentum, but the spin of elementary particles constituting them (electrons, and the quarks in the protons and neutrons of the atomic nuclei). Particles do not necessarily have electric charge to have a spin magnetic moment; the neutron is electrically neutral but has a non–zero magnetic moment, because of its internal quark structure.
Other articles related to "magnetic, magnetic moment, spin magnetic moment, spin":
... A magnetic dipole is the limit of either a closed loop of electric current or a pair of poles as the dimensions of the source are reduced to zero while keeping the magnetic moment constant ... It is a magnetic analogue of the electric dipole, but the analogy is not complete ... In particular, a magnetic monopole, the magnetic analogue of an electric charge, has never been observed ...
... Nuclear magneton Pauli principle Nuclear magnetic resonance Multipole expansion Relativistic quantum mechanics ...
... Flux pinning is the phenomenon that magnetic flux lines cannot move (become trapped, or "pinned") despite the Lorentz force acting on them inside a current-carrying Type II superconductor ... cannot occur in Type I superconductors, since these cannot be penetrated by magnetic fields (Meissner–Ochsenfeld effect) ... The natural magnetic waves that bend around and pin the superconductor in mid space also break into millions of ultra-thin lines and each one carries a flux quantum caused from the ...
... VB), theory of chemical bonding, it is an adequate model for explaining the magnetic properties of electrically insulating narrow-band ionic and covalent non-mo ... In the Stoner model, the spin-only magnetic moment (in Bohr magnetons) per atom in a ferromagnet is given by the difference between the number of electrons per atom in the ... model thus permits non-integral values for the spin-only magnetic moment per atom ...
... Formally, the magnetic permeability is treated as a non-diagonal tensor as expressed by the equation The relation between the angle of rotation of the polarization and the ... when the direction of propagation is parallel to the magnetic field and to R-rotation (clockwise) when the direction of propagation is anti-parallel ... By placing a rod of this material in a strong magnetic field, Faraday rotation angles of over 0.78 rad (45°) can be achieved ...
Famous quotes containing the words moment, spin and/or magnetic:
“Do you mistake me?
I am speaking of living,
of moving from one moment into
the next, and into the
one after, breathing
death in the spring air....”
—Denise Levertov (b. 1923)
“Words can have no single fixed meaning. Like wayward electrons, they can spin away from their initial orbit and enter a wider magnetic field. No one owns them or has a proprietary right to dictate how they will be used.”
—David Lehman (b. 1948)
“We are in great haste to construct a magnetic telegraph from Maine to Texas; but Maine and Texas, it may be, have nothing important to communicate.”
—Henry David Thoreau (18171862)