Format

Send to

Choose Destination
See comment in PubMed Commons below
J Appl Phys. 1991 Apr 15;69(8):6031-3.

Positive holes in magnesium oxide. Correlation between magnetic, electric, and dielectric anomalies.

Author information

1
Department of Physics, San Jose State University, California 95192, USA.
2
ARC

Abstract

Magnetic susceptibility measurements of high purity MgO single crystals (<50-wt. ppm transition metals) by means of a vibrating-sample magnetometer shows an anomaly at 800 K. At the same temperature the electric conductivity increases anomalously, the static dielectric constant epsilon increases from 9 to approximately 150, a pronounced positive surface charge appears, and Fe2+ in the MgO matrix oxidizes to Fe3+. The data are consistent with O2(2-) (peroxy) defects, representing self-trapped, spin-paired positive holes at Mg2+ vacancy sites. Diamagnetic at low temperatures, the holes start to decouple their spins > 600 K, probably forming at first V0 centers (two O- at an Mg2+ vacancy), then V- centers (single O- at an Mg2+ vacancy), and releasing mobile O- states. These O- represent itinerant charge carriers on acceptor levels near the O 2p-dominated valence band and conduct by O- /O2- valency fluctuations. The O- concentration is of the order of 8 X 10(19) cm-3.

PMID:
11538293
[Indexed for MEDLINE]
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Loading ...
    Support Center