Optical and magnetic properties of indium oxides implanted with Cr


Optical and magnetic properties of indium oxides implanted with Cr

Scarlat, C.; Zhou, S.; Vinnichenko, M.; Kolitsch, A.; Bürger, D.; Fassbender, J.; Potzger, K.; Shalimov, A.; Grenzer, J.; Helm, M.; Schmidt, H.

Dilute magnetic oxides are expected to play a key role in the development of electronics using the electron spin rather than its charge as information carrier. Indium oxide (IO), a transparent conductive material, is of potential interest for spintronics [1] due to its unique combination of magnetic, electrical, and optical properties. Highly oxygen deficient Cr:IO co-evaporated films revealed ferromagnetism [2]. In present work, we report the post-growth treatment effect on the structural, electrical, magnetic, and optical properties of Cr-implanted IO films. Cr is chosen as a dopant because of its large magnetic moment in the ionic state, and its antiferomagnetic nature in the bulk, ruling out the extrinsic origin of the ferromagnetism if Cr metal segregation occurs. It is non-trivial to form any ferromagnetic secondary phase of Cr oxide. Polycrystalline and amorphous, ca. 300 nm thick IO films were grown on SiO2/Si substrates using reactive pulsed magnetron sputtering and then implanted with Cr+ ions (1, 2, 3, 4 and 5 at% of Cr). The implantation energy was 120 keV. The magnetic-field dependence of magnetization of 2%Cr:IO showed a weak ferromagnetic behavior at 5K. A reasonable model for the Cr implanted IO films has been developed to extract optical constants from spectroscopic ellipsometry data below 3 eV. [1] C. Scarlat et al., Proceedings IBMM 2008, August 31- September 05, 2008, Dresden, Germany [2] J. Philip et al., Nature materials 5, 298 (2006).

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    E-MRS 2009 Spring Meeting, 08.-12.06.2009, Strasbourg, France

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