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Giant Magnetoresistance in Hybrid Magnetic Nanostructures Including Both Layers and Clusters

Published online by Cambridge University Press:  15 February 2011

P.A. Schroeder ,
P. Holody ,
R. Loloee ,
J. L. Duvail ,
A. BarthÉlemy ,
L.B. Steren ,
R. Morel  and
A. Fert
P.A. Schroeder
Affiliation:
Department of Physics and Astronomy, and Center for Fundamental Materials Research., Michigan State University, East Lansing, Ml 48824-1116.
P. Holody
Affiliation:
Department of Physics and Astronomy, and Center for Fundamental Materials Research., Michigan State University, East Lansing, Ml 48824-1116.
R. Loloee
Affiliation:
Department of Physics and Astronomy, and Center for Fundamental Materials Research., Michigan State University, East Lansing, Ml 48824-1116.
J. L. Duvail
Affiliation:
Laboratoire de Physique des Solides, Université Paris Sud, 91405 Orsay, France.
A. BarthÉlemy
Affiliation:
Laboratoire de Physique des Solides, Université Paris Sud, 91405 Orsay, France.
L.B. Steren
Affiliation:
Laboratoire de Physique des Solides, Université Paris Sud, 91405 Orsay, France.
R. Morel
Affiliation:
Laboratoire de Physique des Solides, Université Paris Sud, 91405 Orsay, France.
A. Fert
Affiliation:
Laboratoire de Physique des Solides, Université Paris Sud, 91405 Orsay, France.
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Abstract

Early experiments to define oscillations in the CIP magnetoresistance (CIP-MR) of Ag/Co analogous to those for tcu < 5nm in Cu/Co were unsuccessful. The MR in this region was very small. Later experiments by Araki using thin (0.6nm ) Co layers produced much larger MRs and lead us to look at the MRs of similar samples more closely. We conclude that the large MR of such samples is associated with the discontinuous nature of the Co layers. The object of the present paper is to combine the high MR associated with the thin Co layers with the field dependence governed by the magnetization reversal in thick, and magnetically soft permalloy (Py) layers. We have measured the CIP-MR of sputtered samples of the [Co(O.4 nm)/Ag(tAg)/Py(tpy)/Ag(tAg)]×15 system with tAg ranging from 1.05 to 4nm and with tpy = 2 or 4nm. We obtain MRs at 4.2K as large as 35% in less than 100e with slopes as high as 5%/Oe. With CPP measurements slopes as high as 10%/Oe have been obtained. Squid magnetometer measurements indicate that, as the temperature increases, there is a crossover to superparamagnetic behaviour and a resulting gross deterioration of the MR slopes at room temperature. Efforts to increase the room temperature sensitivity are described. Detailed measurements of the CPP-MR of the [Co(0.4nm)/Ag(4nm)/Py(tpy)/Ag(4nm)]x20 series of multilayers are consistent with a two spin band model modified to take account of the granular nature of the Co.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 384: Symposium L – Magnetic Ultrathin films, Multilayers and Surfaces , 1995 , 415
Copyright
Copyright © Materials Research Society 1995

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References

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