Compressed bismuth-containing garnet films of replicable low anisotropy field value and devices utilizing same

A magnetically switchable magneto-optic element of high Faraday rotation comprising a monocrystalline gadolinium garnet substrate and an ion implanted epitaxial film supported by said substrate, said epitaxial film being nominally represented by the formula:

• Bi.sub.x M.sub.3-x-z Q'.sub.z' Fe.sub.5-y-z Ga.sub.y Q.sub.z O.sub.12
• wherein, in the epitaxial film prior to ion implantation:
• M is selected from the group consisting of Dy, Ho, Er, Tm, Yb, Lu, Y, Sm, Gd and combinations thereof;
• Q is selected from the group consisting of Mn.sup.3+, In.sup.3+, Sc.sup.3+, Sb.sup.3+, Al.sup.3+, Ge.sup.4+, V.sup.5+ and combinations thereof;
• Q' is a charge-balancing cation having a valence lower than 3+ which is present where Q is comprised of a cation having a valence higher than 3+, Q' being present in an amount such that charge balance is maintained;
• the values of x, y, z and z' are as follows:
• <
• x.ltoreq.1.9
• 0.ltoreq.y.ltoreq.1.35
• 0.ltoreq.z.ltoreq.1.0
• 0.ltoreq.z'.ltoreq.1.0
• y+z.ltoreq.1.4
• the epitaxial film is in compression caused by lattice differential between substrate and epitaxial film, said epitaxial film having a lattice constant greater than said subtrate;
• the combination of the cations comprising said epitaxial film provides a net negative magneto-strictive coefficient;
• the anisotropy field of the epitaxial film is a positive value up to about 8,000 gauss;
• the collapse field of said epitaxial film has a positive value up to about 120 oersteds;
• and,
• the Faraday rotation of said epitaxial film is at least about 0.7 degrees per micron at 632 nm;
• and
• wherein the epitaxial film subsequent to ion implantation has an anisotropy field of positive value lower than said epitaxial film prior to ion implantation.

A light valve comprised of a polarizer, an analyzer and an optically active composite therebetween, said optically active composite having x-y coincident drive line means associated therewith, characterized in that the optically active composite is a magnetically switchable magneto-optic element of high Faraday rotation comprising a monocrystalline gadolinium garnet substrate and an epitaxial film supported by said substrate, said epitaxial film being nominally represented by the formula:

• Bi.sub.x M.sub.3-x-z Q'.sub.z' Fe.sub.5-y-z Ga .sub.y Q.sub.z O.sub.12
• wherein:
• M is selected from the group consisting of Dy, Ho, Er, Tm, Yb, Lu, Y, Sm, Gd and combinations thereof;
• Q is selected from the group consisting of Mn.sup.3+, In.sup.3+, Sc.sup.3+, Sb.sup.3+, Al.sup.3+, Ge.sup.4+, V.sup.5+ and combinations thereof;
• Q' is a charge-balancing cation having a valence lower than 3+ which is present where Q is comprised of a cation having a valence higher than 3+, Q' being present in an amount such that charge balance is maintained;
• the values of x, y, z and z' are as follows:
• <
• x.ltoreq.1.9
• 0.ltoreq.y.ltoreq.1.35
• 0.ltoreq.z.ltoreq.1.0
• 0.ltoreq.z'.ltoreq.1.0
• y+z.ltoreq.1.4
• the epitaxial film is in compression caused by lattice differential between substrate and epitaxial film, said epitaxial film having a lattice constant greater than said substrate;
• the combination of the cations comprising said epitaxial film provides a net negative magneto-strictive coefficient;
• the anisotropy field of the epitaxial film is a positive value up to about 8,000 gauss;
• the collapse field of said epitaxial film :
• has a positive value up to about 120 oersteds;
• and,
• the Faraday rotation of said epitaxial film is at least about 0.7 degrees per micron at 632 nm.

In an optical printer for recording printed information on a radiation-sensitive recording medium, said printer comprised of a source of radiation, means for imposing an image on said radiation and means for receiving and recording said image on a radiation-sensitive recording medium, the improvement which comprises utilizing an image-forming means comprising an array of independently switchable optically activ pixels epitaxially formed on monocrystalline gadolinium garnet substrate, said pixels comprising an epitaxial film nominally represented by the formula:

• Bi.sub.x M.sub.3-x-z Q'.sub.z', Fe.sub.5-y-z Ga.sub.y Q.sub.z O.sub.12
• wherein:
• M is selected from the group consisting of Dy, Ho, Er, Tm, Yb, Lu, Y, Sm, Gd and combinations thereof;
• Q is selected from the group consisting of Mn.sup.3+, In.sup.3+, Sc.sup.3+, Sb.sup.3+, Al.sup.3+, Ge.sup.4+, V.sup.5+ and combinations thereof;
• Q' is a charge-balancing cation having a valence lower than 3+ which is present where Q is comprised of a cation having a valence higher than 3+, Q' being present in an amount such that charge balance is maintained;
• the values of x, y, z and z' are as follows:
• 0<x.ltoreq.1.9
• 0.ltoreq.y.ltoreq.1.35
• 0.ltoreq.z.ltoreq.1.0
• .ltoreq. z'.ltoreq.1.0
• y+z.ltoreq.1.4
• the epitaxial film is in compression caused by lattice differential between substrate and epitaxial film, said epitaxial film having a lattice constant greater than said substrate;
• the combination of the cations comprising said epitaxial film provides a net negative magneto-strictive coefficient;
• the anisotropy field of the epitaxial film is a positive value up to about 8,000 gauss;
• the collapse field of said epitaxial film has a positive value up to about 120 oersteds;
• and,
• the Faraday rotation of said epitaxial film is at least about 0.7 degrees per micron at 632 nm.

A microwave signal processing unit comprising a microwave source, an acousto-optic Bragg cell for receiving microwaves propagated by said microwave source, a laser light source for passing laser light through said acousto-optic Bragg cell, a receiver situated to receive said laser light and an array of independently switchable optically active pixels formed on monocrystalline gadolinium garnet substrate interposed between said acousto-optic Bragg cell and said receiver, said pixels comprising an epitaxial film nominally represented by the formula:

• Bi.sub.x M.sub.3-x-z Q'.sub.z' Fe.sub.5-y-z- Ga.sub.y Q.sub.z O.sub.12
• wherein:
• M is selected from the group consisting of Dy, Ho, Er, Tm, Yb, Lu, Y, Sm, Gd and combinations thereof;
• Q is selected from the group consisting of Mn.sup.3+, In.sup.3+, Sc.sup.3+, Sb.sup.3+, Al.sup.3+, Ge.sup.4+, V.sup.5+ and combinations thereof;
• Q' is a charge-balancing cation having a valence lower than 3+ which is present where Q is comprised of a cation having a valence higher than 3+, Q' being present in an amount such that charge balance is maintained;
• the values of x, y, z and z' are as follows:
• 0<x.ltoreq.1.9
• 0.ltoreq.y.ltoreq.1.35
• 0.ltoreq.z.ltoreq.1.0
• .ltoreq. z'.ltoreq.1.0
• y+z.ltoreq.1.4
• the epitaxial film is in compression caused by lattice differential between substrate and epitaxial film, said epitaxial film having a lattice constant greater than said substrate;
• the combination of the cations comprising said epitaxial film provides a net negative magneto-strictive coefficient;
• the anisotropy field of the epitaxial film is a positive value up to about 8,000 gauss;
• the collapse field of said epitaxial film has a positive value up to about 120 oersteds;
• and,
• the Faraday rotation of said epitaxial film is at least about 0.7 degrees per micron at 632 nm.

A magneto-optic light deflector comprising a monocrystalline gadolinium garnet substrate upon which are supported parallel aligned switchable periodic stripe domains formed by a plurality of parallel strips of an epitaxial film nominally represented by the formula:

• Bi.sub.x M.sub.3-x-z Q'.sub.z' Fe.sub.5-y-a- Ga.sub.y Q.sub.z O.sub.12
• wherein:
• M is selected from the group consisting of Dy, Ho, Er, Tm, Yb, Lu, Y, Sm, Gd and combinations thereof;
• Q is selected from the group consisting of Mn.sup.3+, In.sup.3+, Sc.sup.3+, Sb.sup.3+, Al.sup.3+, Ge.sup.4+, V.sup.5+ and combinations thereof;
• Q' is a charge-balancing cation having a valence lower than 3+ which is present where Q is comprised of a cation having a valence higher than 3+, Q' being present in an amount such that charge balance is maintained;
• the values of x, y, z and z' are as follows:
• 0<x.ltoreq.1.9
• 0.ltoreq.y.ltoreq.1.35
• 0.ltoreq.z.ltoreq.1.0
• 0.ltoreq.z'.ltoreq.1.0
• y+z.ltoreq.1.4
• the epitaxial film is in compression caused by lattice differential between substrate and epitaxial film, said epitaxial film having a lattice constant greater than said substrate;
• the combination of the cations comprising said epitaxial film provides a net negative magneto-strictive coefficient;
• the anisotropy field of the epitaxial film is a positive value up to about 8,000 gauss;
• the collapse field of said epitaxial film has a positive value up to about 120 oersteds;
• and,
• the Faraday rotation of said epitaxial film is at least about 0.7 degrees per micron at 632 nm.