Ferromagnetism induced by clustered Co in Co-doped anatase TiO2 thin films.
We investigated ferromagnetism of a newly discovered ferromagnetic semiconductor Co-doped anatase TiO2 thin film, using the magnetic circular dichroism (MCD) at the Co L(2,3) absorption edges. The magnetic moment was observed to be approximately 0.1 micro(B)/Co in the measurements, but the MCD spectral line shape is nearly identical to that of Co metal, showing that the ferromagnetism is induced by a small amount of clustered Co. With thermal treatments at approximately 400 degrees C, the MCD signal increases, and the moment reaches up to approximately 1.55 micro(B)/Co, which is approximately 90% of the moment in Co metal. In the latter case, the cluster size was observed to be 20-60 nm.
Kim
J-Y
JY
Department of Physics & Electron Spin Science Center, Pohang University of Science and Technology, Pohang, Korea.
Park
J-H
JH
Park
B-G
BG
Noh
H-J
HJ
Oh
S-J
SJ
Yang
J S
JS
Kim
D-H
DH
Bu
S D
SD
Noh
T-W
TW
Lin
H-J
HJ
Hsieh
H-H
HH
Chen
C T
CT