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http://dx.doi.org/10.4283/JKMS.2005.15.2.109

Electronic and Magnetic Properties of Ti1-xMxO2-δ (M=Co and Fe) Thin Films Grown by Sol-gel Method  

Kim, Kwang-Joo (Department of Physics, Konkuk University)
Park, Young-Ran (Department of Physics, Konkuk University)
Ahn, Geun-Young (Department of Physics, Kookmin University)
Kim, Chul-Sung (Department of Physics, Kookmin University)
Park, Jae-Yun (Department of Materials Science and Engineering, University of Incheon)
Abstract
Electronic and magnetic properties of $Ti_{1-x}M_xO_{2-\delta}$ (M=Co and Fe) thin films grown by sol-gel method have been investigated. Anatase and rutile $Ti_{1-x}Co_xO_{2-\delta}$ films were successfully grown on $Al_2O_3$ (0001) substrates and exhibited p-type electrical conductivity while the undoped films n-type conductivity. Room temperature vibrating sample magnetometry measurements on the anatase and rutile $Ti_{1-x}Co_xO_{2-\delta}$ films with same x ($=4.8 at.{\%}$) showed quite similar magnetic hysteresis curves with the saturation magnetic moment of $\~4 {\mu}_B$ per Co ion despite their differences in structural and electronic properties. Such giant magnetic moment is attributable to the unquenched orbital moment of the $Co^{2+}$ ions substituting the octahedral $Ti^{4+}$ sites. Similar ferromagnetic behavior was observed for $Ti_{1-x}Fe_xO_{2-\delta}$ films that are highly resistive compared to the Co doped samples. Saturation magnetic moment was found to decrease for higher x, i.e., $\~2$ and $\~1.5 {\mu}_B$ per Fe ion for x=2.4 and 5.8 at. $\%$, respectively. Conversion electron $M\ddot{o}ssbauer$ spectroscopy measurements predicted the coexistence of $Fe^{2+}$ and $Fe^{3+}$ ions at the octahedral sites of $Ti_{1-x}Fe_xO_{2-\delta}$.
Keywords
ferromagnetism; magnetic moment; orbital moment quenching;
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