Proper and Improper SrRuO3 Phase and Corresponding Itinerant Ferromagnetic Behavior
Gopeshwar Dhar Dwivedi1*, C. J. Li1, T. C. Huang1, Y. C. Liang1, H. C. Huang1, Hsiung Chou1
1Department of Physics, National Sun Yat-Sen University, Kaohsiung, Taiwan
* presenting author:Gopeshwar Dwivedi,
Single crystalline SrRuO3 is a ferromagnetic metal below 165 K and shows low temperature ordered magnetic moment around 1.6 µB/Ru (maximum)[1]. This magnetic moment is less than 2µB/Ru (gSµB), which is expected from low spin state of Ru4+. Even this 1.6 µB/Ru moment is not easy to achieve from polycrystalline SrRuO3, as reported by earlier works [1-5]. In our experiment, it has been observed that Ru deficiency is leading to the formation of secondary phase in the system. The evolution of secondary phase of Sr3Ru2O7 (member of the same Ruddlesden-Popper series) is found to affect the itinerant ferromagnetic behavior of SrRuO3 and because of this secondary phase, achieving desired Curie temperature and magnetic moment is not possible. It has been observed that longer annealing of SrRuO3 causes formation of secondary Sr3Ru2O7 phase which is due to the volatility of RuO2. In this study, by using special processing route, a Curie temperature (Tc) as high as 164 K and low temperature ordered magnetic moment ~1.6 µB/Ru has been achieved for polycrystalline SrRuO3, which is almost equal to the values obtained for SrRuO3 single crystal. Additionally, metal-metal transition and resistivity of our pure phase exhibits smaller resistivity for the system and better magnetic response to those contained minor Sr3Ru2O7 phase.

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Keywords: Itinerant Ferromagnetism, Curie Temperature, Magnetic moment