Method and apparatus for generating electron spin reversal in ferrimagnetic material

A method for inducing repeatable transformation in ferrimagnetic thin film material as change in transmission characteristics of polarized light comprising:

• transiently exposing a target domain of a ferrimagnetic film of a thickness on the order of twice the width of a natural domain of said film to a circularly polarized beam of coherent optical radiation, said beam being of a diameter less than the width of said target domain and said exposing being of an intensity and duration sufficient to induce a change in intrinsic magnetization of said domain according to the circular polarization of said beam, and insufficient to cause irreversible destruction to said domain.

A method for inducing electron spin reversal in selected domains in a ferrimagnetic material comprising:

• exposing a target stripe domain of a ferrimagnetic film to a circularly polarized coherent optical radiation beam, said beam being oppositely polarized relative to inherent magnetization of said target stripe domain, said beam being of a diameter less than the width of said target stripe domain of said film, said beam being directed through said film for an interval insufficient to cause irreversible damage to said target cylinder domain but sufficient to impart angular momentum to reverse electron spin in said ferrimagnetic material in order to generate a cylinder domain and a surrounding toroid domain of a magnetization different from the magnetization of said original stripe domain.

A method for creating an observable domain change in magnetic domain thin film material comprising directing a beam of near diffraction-limited circularly polarized optical radiation at a domain of a ferrimagnetic film with an intensity sufficient to induce a change in observable polarization of optical radiation through said film, and for an interval insufficient to cause irreversible damage to said domain.

A method for photomagnetically storing, altering and retrieving data in a thin film of ferrimagnetic material comprising:

• providing cylinder and toroid domains in pairs in said thin film at preselected locations, said cylinder domains of a first intrinsic magnetization representing a first discrete state and said cylinder domains of a second intrinsic magnetization representing a second discrete state;
• and
• detecting the polarization of optical radiation directed through said preselected locations.