Department of Materials Science and Metallurgy , University of Cambridge , 27 Charles Babbage Road , Cambridge CB3 0FS , United Kingdom.
Materials Engineering , Purdue University , West Lafayette , Indiana 47907 , United States.
ACS Appl Mater Interfaces. 2018 May 30;10(21):18237-18245. doi: 10.1021/acsami.8b03837. Epub 2018 May 18.
Electric field control of magnetism is a critical future technology for low-power, ultrahigh density memory. However, despite intensive research efforts, no practical material systems have emerged. Interface-coupled, composite systems containing ferroelectric and ferri-/ferromagnetic elements have been widely explored, but they have a range of problems, for example, substrate clamping, large leakage, and inability to miniaturize. In this work, through careful material selection, design, and nanoengineering, a high-performance room-temperature magnetoelectric system is demonstrated. The clamping problem is overcome by using a vertically aligned nanocomposite structure in which the strain coupling is independent of the substrate. To overcome the leakage problem, three key novel advances are introduced: a low leakage ferroelectric, NaBiTiO; ferroelectric-ferrimagnetic vertical interfaces which are not conducting; and current blockage via a rectifying interface between the film and the Nb-doped SrTiO substrate. The new multiferroic nanocomposite (NaBiTiO-CoFeO) thin-film system enables, for the first time, large-scale in situ electric field control of magnetic anisotropy at room temperature in a system applicable for magnetoelectric random access memory, with a magnetoelectric coefficient of 1.25 × 10 s m.
电场控制磁性是低功耗、超高密度存储器的未来关键技术。然而，尽管研究工作密集，实用的材料体系仍未出现。界面耦合的、包含铁电体和亚铁磁/铁磁元件的复合材料体系已经得到广泛探索，但它们存在一系列问题，例如基底夹持、大漏电流和无法小型化。在这项工作中，通过仔细的材料选择、设计和纳米工程，展示了一种高性能的室温磁电系统。通过使用垂直排列的纳米复合材料结构克服了夹持问题，其中应变耦合与基底无关。为了克服漏电流问题，引入了三个关键的新颖进展：低漏电流铁电体 NaBiTiO；不导电的铁电-亚铁磁垂直界面；以及通过薄膜和掺铌 SrTiO 基底之间的整流界面实现电流阻断。新的多铁性纳米复合材料（NaBiTiO-CoFeO）薄膜系统首次在适用于磁电随机存取存储器的室温下实现了大规模的磁各向异性的原位电场控制，磁电系数为 1.25×10^-5 s m。
