There are two main ways to create net
spin populations in semiconductors. One is called
optical pumping. It uses light of one specified
polarization (a type of spin of its own) to knock
electrons of the right orientation (mostly all spin up
for instance) to an energy level which allows them to
be free to move in an electric field.The electrons
moving in this context form an electrical current.
Because the specifically polarized light interacts and
frees
mostly one kind of electron (spin up or
spin down) the free electrons
turn out to have
a net spin population. Another method for creating
spin populations involves running an electrical
current through a ferromagnetic contact into a
semiconductor, for example from an Iron (Fe) contact
into Gallium Arsenide (GaAs). Because the free
electrons in Fe are spin polarized it produces a
current which is spin polarized. When the electrons
leave the magnetic material, they remain aligned and
this results in a net electron spin population in the
semiconductor.
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Electrons and Spin! What is Spin? Spin and Light! Spin Precession! Spin Transport! Spin Populations! Continue on to learn about Spin Transistors! |