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Neutron and X-Ray Scattering Studies of (FeF2) M (CoF2)n Multilayers

Published online by Cambridge University Press:  03 September 2012

D. Lederman ,
D. P. Belanger ,
J. Wang ,
S-J. Han ,
C. Paduani ,
C. A. Ramos  and
R. M. Nicklow
D. Lederman
Affiliation:
Dept. of Physics, University of California, San Diego, La Jolla, CA 92093–0319 Dept. of Physics, University of California, Santa Barbara, CA 93106
D. P. Belanger
Affiliation:
Department of Physics, University of California, Santa Cruz, CA 95064
J. Wang
Affiliation:
Department of Physics, University of California, Santa Cruz, CA 95064
S-J. Han
Affiliation:
Department of Physics, University of California, Santa Cruz, CA 95064
C. Paduani
Affiliation:
Department of Physics, University of California, Santa Cruz, CA 95064 Department of Physics, Univ. Fed. de Santa Catarina, Florianopolis, Brazil
C. A. Ramos
Affiliation:
Dept. of Physics, University of California, Santa Barbara, CA 93106 Centro AtòMico Bariloche, 8400 Bariloche, Rio Negro, Argentina
R. M. Nicklow
Affiliation:
Solid State Division, Oak Ridge National Laboratory, Oak Ridge TN 37831
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Abstract

We have performed elastic neutron scattering measurements of the staggered magnetization in (FeF2) M (CoF2) n superlattices. Thermal expansion Measurements, which are proportional to the magnetic contribution to the specific heat, were also carried out using high resolution x-ray diffraction. One of the two measured samples has thicknesses of M = n = 4.5 and the other M = 26 and n = 28 Monolayers, as determined from high angle x-ray θ — 2θ scans. In the M = n = 4.5 sample, only one transition is observed at T/v = 62.9K. Analysis of the neutron data, including the rounding effects, indicates an effective β ≈ 0.42. This does not compare well with the 3D Ising exponent β = 0.325. The X-ray data also show the existence of only one specific heat anomaly at T = 62.8 K. For the M = 26, n = 28 sample, dips in the staggered magnetization and peaks in the thermal expansion were observed at T ≈ 40 K and 74 K. The higher temperature anomaly, associated primarily with the FeF2 layers, is sharper than the lower one, which is presumably rounded by the staggered ordering field imposed by the long range order in the FeF2 regions on the CoF2 regions.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 313: Symposium Q1 – Magnetic Ultrathin Films, Multilayers and Surfaces/Magnetic Interfaces-Physics and Characterizations , 1993 , 333
Copyright
Copyright © Materials Research Society 1993

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References

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