Negligible magnetism in excellent structural quality Cr(x)Ti(1-x)O(2) anatase: contrast with high-T(C) ferromagnetism in structurally defective Cr(x)Ti(1-x)O(2).
We reexamine the mechanism of ferromagnetism in doped TiO(2) anatase, using epitaxial Cr:TiO(2) with excellent structural quality as a model system. In contrast to highly oriented but defective Cr:TiO(2) (approximately 0.5 micro(b)/Cr), these structurally superior single crystal films exhibit negligible ferromagnetism. Similar results were obtained for Co:TiO(2). We show for the first time that charge-compensating oxygen vacancies alone, as predicted by F-center mediated exchange, are not sufficient to activate ferromagnetism. Instead, the onset of ferromagnetism correlates with the presence of structural defects.
Kaspar
T C
TC
Pacific Northwest National Laboratory, Richland, Washington 99352, USA.
Heald
S M
SM
Wang
C M
CM
Bryan
J D
JD
Droubay
T
T
Shutthanandan
V
V
Thevuthasan
S
S
McCready
D E
DE
Kellock
A J
AJ
Gamelin
D R
DR
Chambers
S A
SA