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Magnetic Field Sensitive Devices Using High Tc Magnetic Superconductors

IP.com Disclosure Number: IPCOM000106981D
Original Publication Date: 1992-Jan-01
Included in the Prior Art Database: 2005-Mar-21
Document File: 2 page(s) / 85K

Publishing Venue

IBM

Related People

Malozemoff, AP: AUTHOR

Abstract

A number of magnetic rare earth ions can be substituted completely for yttrium in the Ba2YCu3O7 high temperature superconductor and have a negligible effect on the resistive transition when measured in zero field. This result indicates that the exchange scattering which normally gives an Abrikosov-Gorkov pair breaking suppression of the superconducting transition temperature is essentially absent in these materials. An electromagnetic interaction between the moment of the magnetic ions and the superconductivity will still occur. In the absence of field and as long as the temperature is above any magnetic ordering temperature, the magnetic ions remain disordered, and their effect on the superconductivity remains negligible because there is no net electromagnetic field.

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Magnetic Field Sensitive Devices Using High Tc Magnetic Superconductors

       A number of magnetic rare earth ions can be substituted
completely for yttrium in the Ba2YCu3O7 high temperature
superconductor and have a negligible effect on the resistive
transition when measured in zero field.  This result indicates that
the exchange scattering which normally gives an Abrikosov-Gorkov pair
breaking suppression of the superconducting transition temperature is
essentially absent in these materials.  An electromagnetic
interaction between the moment of the magnetic ions and the
superconductivity will still occur.  In the absence of field and as
long as the temperature is above any magnetic ordering temperature,
the magnetic ions remain disordered, and their effect on the
superconductivity remains negligible because there is no net
electromagnetic field.  But either in the presence of the field or
below a magnetic transition temperature, a field appears, and then
there may be coupling to the superconductivity.  This effect can be
used to make magnetoresistive sensors, magnetic tunneling devices and
magnetically sensitive FETs.

      The couplings between the magnetic atoms (rather than the
couplings between the magnetic and superconducting systems), may be
antiferromagnetic, ferromagnetic or even spin-glass like.  The
ferromagnetic couplings will lead to enhanced permeabilities and will
be of greatest interest for devices.  If the magnetic moments are
oriented parallel to the planes, the interaction with
superconductivity will be reduced while if they are oriented
perpendicular to the planes, the interaction is increased.

      These devices use mixtures of magnetic rare earths on the
yttrium site, and yield devices giving ferromagnetic or strong
paramagnetic susceptibility.  The electromagnetic coupling of the
resulting electromagnetic field, controlled by an applied field, will
enhance the competition with superconductivity.  A variety of
superconducting properties can be sensitively changed by application
of an...