Zheng H, Wang J, Lofland S E, Ma Z, Mohaddes-Ardabili L, Zhao T, Salamanca-Riba L, Shinde S R, Ogale S B, Bai F, Viehland D, Jia Y, Schlom D G, Wuttig M, Roytburd A, Ramesh R
Department of Materials Science and Engineering, University of Maryland, College Park, MD 20742, USA.
Science. 2004 Jan 30;303(5658):661-3. doi: 10.1126/science.1094207.
We report on the coupling between ferroelectric and magnetic order parameters in a nanostructured BaTiO3-CoFe2O4 ferroelectromagnet. This facilitates the interconversion of energies stored in electric and magnetic fields and plays an important role in many devices, including transducers, field sensors, etc. Such nanostructures were deposited on single-crystal SrTiO3 (001) substrates by pulsed laser deposition from a single Ba-Ti-Co-Fe-oxide target. The films are epitaxial in-plane as well as out-of-plane with self-assembled hexagonal arrays of CoFe2O4 nanopillars embedded in a BaTiO3 matrix. The CoFe2O4 nanopillars have uniform size and average spacing of 20 to 30 nanometers. Temperature-dependent magnetic measurements illustrate the coupling between the two order parameters, which is manifested as a change in magnetization at the ferroelectric Curie temperature. Thermodynamic analyses show that the magnetoelectric coupling in such a nanostructure can be understood on the basis of the strong elastic interactions between the two phases.
我们报道了纳米结构的钛酸钡-钴铁氧体铁电体中铁电和磁序参量之间的耦合。这促进了存储在电场和磁场中的能量的相互转换，并在包括换能器、场传感器等在内的许多器件中发挥重要作用。通过脉冲激光沉积从单一的钡-钛-钴-铁氧化物靶材在单晶钛酸锶（001）衬底上沉积了这种纳米结构。这些薄膜在平面内和平面外都是外延的，在钛酸钡基体中嵌入了自组装的六方阵列钴铁氧体纳米柱。钴铁氧体纳米柱尺寸均匀，平均间距为20至30纳米。温度相关的磁性测量说明了两个序参量之间的耦合，这表现为在铁电居里温度下磁化强度的变化。热力学分析表明，这种纳米结构中的磁电耦合可以基于两相之间的强弹性相互作用来理解。
