The Spin Of The Electron Essay

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The spin of the electron is an intrinsic angular momentum that is separate from the angular momentum due to its orbital motion. The magnitude of the projection of the electron 's spin along an arbitrary axis is, implying that the electron acts as a Fermion by the spinstatistics theorem. Like orbital angular momentum, the spin has an associated magnetic moment, the magnitude of which is expressed as.   3 q  2 m ( e ) In a solid the spins of many electrons can act together to affect the magnetic and electronic properties of a material, for example endowing it with a permanent magnetic moment as in a ferromagnet. In many materials, electron spins are equally present in both the up and the down state, and no transport properties are dependent on spin. A spintronic device requires generation or manipulation of a spinpolarized population of electrons, resulting in an excess of spin up or spin down electrons. The polarization of any spin dependent property X can be written as. P ( X )  X   X  X   X  A net spin polarization can be achieved either through creating an equilibrium energy split between spin up and spin down. Methods include putting a material in a large magnetic field (Zeeman effect), the exchange energy present in a ferromagnet or forcing the system out of equilibrium. The period of time that sucha nonequilibrium population can be maintained is known as the spin lifetime. In a diffusive conductor, a spin diffusion length can be defined as the distance over
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