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Shanghai Institute of Ceramics, Chinese Academy of Sciences
Synthetic Single Crystal Research Center
中 国 科 学 院 上 海 硅 酸 盐 研 究 所 人 工 晶 体 中 心
Mesoscale Interfacial Dynamics in Magnetoelectric Nanocomposites
磁电复合材料中的介观界面动力学
Speaker：Prof. D. Viehland
Virginia Polytechnic Institute and State University
Dept. Materials Science and Engineering, Virginia Tech, Blacksburg, VA 24061 USA
时间： 2016年3月 7日（星期一）上午9:30
地点：长宁园区4号楼14楼2号会议室
Prof. Dr. Dwight Viehland is currently chair of Electronics Division, American Ceramic Society and the member of American Physical Society, Materials Research Society, Microscopy Society of America and Institute of Electrical and Electronic Engineers. He is also the edit of Journal of the American Ceramic Society and the reviewer of Journal of Applied Physics, Applied Physics Letters, Journal American Ceramic Society, Journal of Materials Research, Physical Review, Physical Review Letters, et al. His research interests include physics of materials, physical ceramics and metallurgy, electrical and dielectric properties of materials, structural property relationships, ferroelectrics and piezoelectrics, mesoscopic/nanometer physics and the effects of disorder on phase transformation, relaxation and dynamics in glassy systems, actuators, transducers and applied acoustics, electrical and transport properties of conducting oxides, and polymers for functional applications.
Abstract
Both heterostructural and vertically integrated two phase ME epitaxial thin layers have been fabricated by various deposition methods. With regards to vertically integrated nanostructures, our investigations have shown various phase architectures of self-assembled BiFeO3-CoFe2O4 (BFO-CFO) thin films on differently oriented SrTiO3 (STO) and Pb(Mg1/3Nb2/3)O3-xat%PbTiO3 (PMN-x%PT) substrates [40]. CFO forms segregated square, stripe, and triangular nanopillars embedded in a coherent BFO matrix on (001)-, (110)- and (111)-oriented substrates, respectively. Nanostructures with an aspect ratio of up to 5:1 with a prominent magnetic anisotropy were obtained on both (001) and (110) substrates along out-of-plane and in-plane directions. Magnetic easy axis rotation from in-plane to out-of-plane directions was realized through aspect ratio control. These studies established a detailed relationship of magnetic anisotropy with specific shapes and dimensions of ordered magnetic arrays. The results suggest a way to effectively control the magnetic anisotropy in patterned ferromagnetic oxide arrays with tunable shape, aspect ratio, and elastic strain conditions of the nanostructures. Using an epitaxial engineering approach, many different types of nanostructures are seemingly possible. It offers the ability to change the balance of terms in the free energy by which to tune the magnetic anisotropy via shape, and also as we will show by electric field.
These two phase layers, and of CFO heterostructures, on PMN-x%PT have pronounced magnetoelectric effects. In particular, large E-field tunable magnetic anisotropies were found. For PMN-x%PT substrate compositions near a morphotropic phase boundary (MPB), both volatile and non-volatile effects have been reported, which can be tuned with substrate composition. This opens up the unique possibility to develop giant ME materials with unique multi-state reconfigurable properties, with and without memory.
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