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APS » Journals » Phys. Rev. Lett. » Volume 80 » Issue 17
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Phys. Rev. Lett. 80, 3815–3818 (1998)

Magnetoresistance of Chromium Dioxide Powder Compacts

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J. M. D. Coey*, A. E. Berkowitz, Ll. Balcells†, and F. F. Putris
Center for Magnetic Recording Research, University of California, San Diego, La Jolla, California 92093

A. Barry
Physics Department, Trinity College, Dublin 2, Ireland

Received 9 September 1997; published in the issue dated 27 April 1998

Cold-pressed powders of the half-metallic ferromagnet CrO2 are dielectric granular metals. Hysteretic magnetoresistance with maxima at the coercive field arises from interparticle contacts. Dilution with insulating antiferromagnetic Cr2O3 powder reduces the conductivity by 3 orders of magnitude, but enhances the magnetoresistance ratio which reaches 50% at 5K. The negative magnetoresistance is due to tunneling between contiguous ferromagnetic particles along a critical path with a spin-dependent Coulomb gap.

© 1998 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevLett.80.3815
DOI:
10.1103/PhysRevLett.80.3815
PACS:
72.15.Gd, 73.40.Gk, 75.50.Cc, 81.20.Ev

*Permanent address: Physics Department, Trinity College, Dublin 2, Ireland.

†Permanent address: ICMAB, Campus UAB, E-08019 Bellaterra, Spain.

 
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