Apparatus and method for writing and reading digital information on a magnetic memory including a superconducting material
AssigneeSemiconductor Energy Laboratory Co., Ltd.
InventorYasuhiko Takemura
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Abstract
An apparatus and a method for writing and reading digital information on a magnetic memory are disclosed. In the apparatus, no mechanical contact between the memory and a magnetic detection means is made because the magnetic state of a respective domain is detected by detecting change of the whole magnetic fluxes induced by entire domains formed on the memory. The writing and reading operation are carried out by scanning the domain with beam irradiation in order to destruct superconductivity or ferromagnetic characteristics of the domain resulting in trapping or releasing of magnetic fluxes. The change in magnetic flux is detected by the detection means.
Claims22
A method for writing digital information on a magnetic memory comprising the steps of:
- inserting magnetic fluxes into storage domains formed on a memory consisting of a superconducting material by pinning effect;
- and
- selectively and sequentially irradiating said storage domains formed on said memory and having magnetic fluxes inserted therein for heating them beyond the critical temperature of said material.
The method for writing digital information as claimed in claim wherein said irradiation is carried out with laser beams.
A method for reading digital information on a magnetic memory comprising the steps of:
- scanning superconducting storage domains having non-superconducting openings therein and formed on a memory consisting of a superconducting material in which magnetic fluxes have been selectively trapped by said storage domains in accordance with information stored in said memory, said scanning being performed in a magnetic field having the same direction to the magnetic fluxes, said scanning further being carded out by irradiation in order to cause phase transition of said material between its superconducting phase and its normal conducting phase through elevation and fall of the temperature of the domain being irradiated;
- and
- detecting change in magnetic fluxes induced by said memory during said scanning, wherein the digital information in said magnetic memory is determined from said change in magnetic fluxes.
A method for writing digital information on a magnetic memory comprising the steps of:
- generating a magnetic flux in the magnetic memory by flowing superconducting current through a continuous superconducting line consisting of a superconducting material in which a plurality of storage domains are formed around non-superconducting openings;
- selectively and sequentially irradiating said storage domains formed on said memory for heating them beyond the critical temperature of said material;
- and
- removing said superconducting current from said superconducting line.
A method for writing digital information on a magnetic memory comprising the steps of:
- generating a magnetic field in the magnetic memory not more than the lower critical field of a superconducting material:
- and
- selectively and sequentially irradiating storage domains having non-superconducting openings therein formed on a memory consisting of said superconducting material for heating them beyond the critical temperature of said material.
A method for reading digital information on a magnetic memory comprising the steps of:
- scanning storage domains formed on a memory consisting of a superconducting material in which magnetic fluxes have been selectively trapped by said storage domains in accordance with information stored in said memory, said scanning being carried out by irradiation in order to cause phase transition of said material from its superconducting phase to its normal conducting phase through elevation of the temperature of the domain being irradiated;
- and
- detecting change in magnetic fluxes induced by said memory during said scanning, wherein the digital information in said magnetic memory is determined from said change in magnetic fluxes.
An apparatus for writing and reading digital information on a magnetic memory comprising:
- a memory consisting of a superconducting material in which magnetic fluxes are selectively trapped by a number of storage domains formed therein in accordance with information to be stored in said memory;
- a magnetic field detection means for detecting the change in magnetic fluxes in one direction throughout said memory;
- a beam irradiation means for selectively irradiating one of said storage domains with a beam;
- and
- a magnetic field application device for applying a magnetic field to said memory.
Dependencies are inferred from the claim text.