EPL is available also on-line on www.epljournal.org
Subscriber Authentication Point
Home All issues Volume 57/ 6 Article
Issue Europhys. Lett.
Volume 57, Number 6, March 2002
Page(s) 866 - 871
Section Condensed matter: electronic structure, electrical, magnetic, and optical properties
DOI http://dx.doi.org/10.1209/epl/i2002-00590-3

DOI: 10.1209/epl/i2002-00590-3


Europhys. Lett., 57 (6) , pp. 866-871 (2002)

Strongly enhanced tunneling magnetoresistance in granular films of $\chem{Co}$ clusters in a $\chem{CO_{2}}$ matrix: Evidence for a cluster-surface/matrix interaction

H. Zare-Kolsaraki, B. Hackenbroich and H. Micklitz

II. Physikalisches Institut, Universität zu Köln Zülpicher Str. 77, 50937 Köln, Germany

micklitz@ph2.uni-koeln.de

(Received 8 October 2001; accepted in final form 7 January 2002)

Abstract
A new granular system, namely, $\chem{Co}$ clusters embedded in solid $\chem{CO_{2}}$, has been prepared by the co-deposition of well-defined $\chem{Co}$ clusters (mean diameter $L \simeq 4.2$ $\un{nm}$, and $\chem{CO_{2}}$ molecules onto a cold substrate. This system shows a temperature-dependent tunneling magnetoresistance (TMR) which has a value of 31(2)% at 2.5 $\un{K}$. Using Jullière's model this value corresponds to a spin-polarisation |P| = 0.68(2) of the tunneling electrons, compared to P = 0.42 for granular $\chem{Co/Xe(Kr)}$ or planar $\chem{Co/Al_{2}O_{3}/Co}$. We interpret this enhancement of P as caused by a cluster-surface/matrix interaction.

PACS
72.15.Gd - Galvanomagnetic and other magnetotransport effects.
73.40.Gk - Tunneling.
73.40.Rw - Metal-insulator-metal structures.


© EDP Sciences 2002