Low field intergranular tunneling effect in CrO{sub 2} nanoparticles and characterization of the barriers

Journal Article · Fri Jun 01 04:00:00 EDT 2001 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.1362641· OSTI ID:40203864

Dai, Jianbiao; Tang, Jinke

The magnetoresistance (MR) and microstructures of half-metallic CrO{sub 2} nanoparticle systems were studied. Using field alignment, the needle-shaped CrO{sub 2} single domain particles were aligned in the same orientation. The MR of this structure showed a magnetic junction-like behavior with two well-separated peaks in the MR at coercivity fields and the MR of the aligned CrO{sub 2} particles reached {gt}41% at a relatively low field of about 1000 Oe. The magnetotransport mechanism was analyzed in terms of spin dependent tunneling between CrO{sub 2} nanoparticles. Using transmission electron microscopy, x-ray diffraction, and x-ray photoelectron spectroscopy techniques, the intergranular tunneling barrier was characterized to be a very thin Cr{sub 2}O{sub 3} interface layer between the CrO{sub 2} particles. Temperature dependence of MR and conductivity in cold-pressed CrO{sub 2} nanopowders were studied. The MR significantly decreased with increasing temperature and the spin independent hopping conduction is suggested to be responsible for the suppression of MR at high temperature. {copyright} 2001 American Institute of Physics.

• Sponsoring Organization: (US)
• OSTI ID: 40203864
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 11 Vol. 89; ISSN 0021-8979
• Publisher: The American Physical Society
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ALIGNMENT
MAGNETORESISTANCE
ORIENTATION
PHOTOELECTRON SPECTROSCOPY
PHYSICS
SPIN
TEMPERATURE DEPENDENCE
TRANSMISSION ELECTRON MICROSCOPY
TUNNELING
X-RAY DIFFRACTION