Bell Telephone Laboratories

Roy C LeCraw

Ernst M Gyorgy

Stuart L Blank

Raymond Wolfe

Lars C Luther

Devices based on epitaxial garnet layers that exhibit a high magnetic anisotropy are disclosed. These garnet layers are produced by introducing a Co.sup.2+ or a species with 1, 2, 4, or 5 electrons in a 4d or a 5d electron orbital in the octahedral site of the garnet in conjunction with a typical anisotropy producing combination on the dodecahedral site. The contribution to magnetic anisotropy due to the typical combination on the dodecahedral site and the appropriate ion in an octahedral site is complementary.

Devices depending on garnet materials

Devices based on epitaxial garnet layers which exhibit a substantial contribution to the magnetic anisotropy other than that attributable to the presence of magnetic rare earth ions are disclosed. These garnet layers are produced by introducing Co.sup.2+ or a species with 1, 2, 4, or 5 electrons in a 4d or 5d electronic orbital in the octahedral site of the garnet. It is possible to produce epitaxial garnets having low damping constants, as determined by resonance line widths on the order of 100 Oe, and K.sub.u 's on the order of 300,000 ergs/cm.sup.3.

Advantageous garnet based devices

A method is disclosed for suppressing hard bubbles in epitaxial magnetic garnet films. The method comprises annealing in an essentially inert atmosphere and renders the annealed film incapable of sustaining hard bubbles.

Process for suppressing hard bubbles in magnetic bubble devices

Members of a class of garnet compositions of particular crystallographic orientation are usefully incorporated in magnetic memory devices which depend for their operation on the positioning of single wall domains ('bubbles'). Such compositions, ordinarily in the form of a supported layer defining a (110) orientation, manifest high limiting bubble velocity, thereby making possible high record and retrieval rates. Compositions invariably contain some lanthanum in the dodecahedral site. Increased limiting velocity is attributed to in-plane anisotropy, in turn, dependent upon partial lanthanum occupation. Depending upon composition, required unique easy direction out of the plane may be as-grown, stress induced, or a combination. Appropriate garnet substrates of required lattice parameters are described.

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Summit, NJ, United States of America

Roy C LeCraw