International Business Machines Corporation

Ralph R Ruf

Richard Joseph Gambino

Michael John Brady

Lia Krusin-Elbaum

Nestor A Bojarczuk, Jr

Nestor Alexander Bojarczuk, Jr

Elia Zeldov

Frederic Holtzberg

Benjamin Welber

A magneto-optic memory and a magnetic material is described incorporating a polarized light beam directed towards a magnetic material and an analyzer for intercepting the polarized light beam after passing through the magnetic material or after being reflected by the magnetic material. The magnetic material includes a matrix of metal such as iron, cobalt, nickel, and alloys thereof and a plurality of separated phases distributed in the matrix such as EuS, EuO, EuOTb, PtMnSb, MnAs, MnBi, MnSb, CrO.sub.2, CrTe, GdN, Gd.sub.4 C, other compounds of a rare earth element and manganese compounds. Terbium or neodymium may be dissolved in the matrix of metal and in the plurality of separated phases. The invention overcomes the problem of providing a magnetic material having a Curie point above room temperature, a square perpendicular hysteresis loop at room temperature, a large magneto-optic rotation at the wavelength of interest and a deposition temperature suitable depositing on polymer substrates.

Composite magneto-optic memory and media

A method and apparatus for storing data and for reducing the magnetic moment of a ferromagnetic material is provided incorporating a magnetic film, a blanket or patterned film of germanium adjacent the magnetic film, and means for heating the interface of the two films to at least 200.degree. C. to permit diffusion of the germanium into the magnetic film and thereby reduce the magnetic moment. The invention overcomes the problem of forming recording tracks on storage media and patterning magnetic films for inductive and magneto resistive heads for retrieving data from moving storage media.

Magnetic film patterning by germanium or silicon diffusion

A magneto-optic memory and storage medium with the ability to directly write or overwrite ones and zeros at recording speed is described incorporating a radiant energy source, a control circuit for adjusting the power of the radiant energy beam and magneto-optic medium having a three layer sandwich comprising a magnetic bias layer, storage layer, and a switching layer therebetween functioning to switch from an antiferromagnetic state at low temperatures to a ferromagnetic state at temperatures above T.sub.AF. The invention overcomes the problem of direct overwrite of ones and zeros on magneto-optic media.

Magneto-optic memory allowing direct overwrite of data

A non-volatile random access memory is described incorporating a plurality of memory cells, each memory cell having a Hall effect device including amorphous magnetic material and a switch for directing current through the flail effect device. An array of memory cells are interconnected by word lines, current lines, and bit lines. The invention overcomes the problem of a rugged non-volatile random access memory with long term reliability.

Magnetic non-volatile random access memory

An apparatus and method for imaging the magnetic structure and the magnetic domains of a sample is described incorporating a scanning tunneling microscope (STM), a voltage generator for varying the voltage on the tip, an ammeter for measuring the current through the tip, circuitry to determine the tip voltage at zero current and a current source for passing current longitudinally through the sample. The invention may further include an applied magnetic field in the plane of the sample and orthogonal to current passing through the sample. A high density non-volatile memory is described incorporating the above apparatus except for the applied magnetic field and further incorporating a layer of ferromagnetic material having magnetic domains therein indicative of information.

Magnetic STM with a non-magnetic tip

A thermochemical magnetic generator system utilizes a gas, preferably hydrogen, and a material, such as LaCo.sub.5, which varies in magnetization upon addition of the gas to the material to generate electricity from a magnetic circuit which includes the magnetizable material in the circuit. When the gas partial pressure is reduced or heat is applied to the material which has combined with the gas, then the gas is driven off in a thermochemical reaction which reverses the magnetization of the system. In particular, the addition of hydrogen gas to LaCo.sub.5 reduces the magnetization and its removal from the material increases the magnetization. Rapid reversal of the pressure cycle or heating and cooling cycles with a plurality of chambers through which the gas is admitted and exhausted reversibly can be used as a source of electricity.

Thermochemical magnetic generator

There is disclosed herein a relatively low-cost, high density postable storage medium which comprises adjacent thin layers of two or more materials which react upon heating to form a reaction product with optical, magnetic or electrical properties different from the corresponding properties of the reactant materials. Thus, utilizing reactant layers such as aluminum and selenium, the heating results in a reaction product of Al.sub.2 Se.sub.3. The heating agent is notably a laser beam.

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Ralph R Ruf