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Detailed Program
Paper Number : TF-O05
Time Frame : 17:31~17:43
Presentation Date : Friday, 28, November
Session Name : Thin Films & Layers
Session Chair 1# : Soon-Gil Yoon
Session Chair 2# : Hiroshi Funakubo
Epitaxial growth and the electric/magnetic properties of magneto-electric Cr2O3 thin film
Takeshi YOKOTA
Nagoya Institute of Technology
Keywords: Epitaxial growth, Magneto-electric Effect, Compressive stress

Magneto-electric (ME) materials have attracted much attention as a new generation of magneto-electronics, because magnetic or ferroelectric properties can be controlled by an external electric or magnetic field. Cr2O3 is one of the typical ME material and many researches have been performed. Recently, Iyama et.al reported magnetic and electric order in Cr2O3 single crystal under a high electric and magnetic field in room temperature. [1] We focused an epitaxial Cr2O3 thin film having epitaxial stress, because we expected the similar ferromagnetic order induced by stress in Cr2O3. It is also expected to reduce the external magnetic field for obtaining the electric polarization. In this presentation, we prepared Cr2O3 epitaxial film having different epitaxial stress and investigated the magnetic properties.
The Cr2O3 thin films were prepared using a radio-frequency (RF) magnetron sputtering method. Cr2O3-sintered ceramic was used as the target. A c-cut Al2O3 and Nb-doped SrTiO3 111 single crystal were used as a substrate. Pt was deposited as a bottom electrode for c-Al2O3 substrate. A mixture of Ar and O2 was used as the sputtering gas; the ratio was 32: 1. The RF power was 60 W. The growth temperature was 530 ¡ÆC. The thickness was fixed at 30 nm. The surface morphology was measured using Atomic Force Microscope. The polarization curves measured using a ferroelectric property measurement system (FCE-1). A compressive stress measured using in/out-of-plane X-ray diffraction (XRD). The magnetic properties were measured using a vibrating sample magnetometer.
The RHEED patterns revealed the films are epitaxially grown on the both Pt/c-Al2O3 and SrTiO3 substrates. It is also revealed that the both film has epitaxial compressive stress in the films. The compressive stress estimated using XRD of each film is 0.7 GPa and 3.04 GPa, respectively. Figure 1 showed magnetic hysteresis curves of samples. The magnetization curves of the sample deposited on SrTiO3 is larger than that of Pt/c-Al2O3. This results are more likely due to differences in the compressive stress.

References:
[1]A. Iyama. et. al, Phys. Rev. B87(2013) pp 180408-1.
Acknowledgements : This research was supported in part by a Grant-in-Aid for Challenging Exploratory Research (26600100) from the Japan Society for the Promotion of Science