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Preparation of Ferromagnetic Films From Eu2O3

IP.com Disclosure Number: IPCOM000110013D
Original Publication Date: 1992-Oct-01
Included in the Prior Art Database: 2005-Mar-25
Document File: 2 page(s) / 63K

Publishing Venue

IBM

Related People

Gambino, RJ: AUTHOR [+2]

Abstract

Disclosed is a way to deposit ferromagnetic, magneto-optic (MO) films of rare earth doped Eu1O1 from nonmagnetic Eu2O3. Eu2O3 costs substantially less than Eu1O1 and has better long term stability.

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Preparation of Ferromagnetic Films From Eu2O3

       Disclosed is a way to deposit ferromagnetic,
magneto-optic (MO) films of rare earth doped Eu1O1 from nonmagnetic
Eu2O3.  Eu2O3 costs substantially less than Eu1O1 and has better long
term stability.

      Ferromagnetic Eu1O1, evaporated from an Eu1O1 source, is a
promising but expensive magneto-optic recording media with a kerr
rotation that is about 20 times larger than present MO recording
media [1,2].  The addition of a trivalent rare earth such as terbium
(Tb) serves to raise the coercivity (Hc) and Curie temperature (Tc).
The ferromagnetic Curie temperature of Eu1O1 (60~K) can be raised to
about 200~K by doping.  This results in the Eu1O1 rocksalt structure
with Tb occupying the Eu sites and a vacancy for each added Tb at the
oxygen sites.  The extra electrons donated by the Tb strengthen the
exchange between the rare earth atoms and raise Tc.  Coercivity
increases due to the strong crystal field interaction with the Tb
atom.

      Coevaporating a trivalent rare earth such as Tb with
nonmagnetic Eu2O3 also results in the rocksalt Eu1O1 structure, with
similarly enhanced Tc and Hc.  When Tb is coevaporated with Eu2O3 a
ferromagnetic rocksalt phase with a preferred <111> orientation is
formed.  Excess rare earth is compensated by vacancies.  This is
unexpected since Eu2O3 has the body centered cubic structure and
Eu1O1 has a much smaller face centered NaCl structure.  The figure
plots the magnet...