题目：Magnetic tunnel junction with a ferroelectric barrier: towards quaternary state device and electric field control of magnetic state
报告人：Prof. Qi Li（Department of Physics and Department, Pennsylvania State University，USA）
摘要：
Most spintronic devices are currently based on magnetic tunnel junctions (MTJs), in which the parallel and antiparallel alignments of the two electrode magnetizations represent the two logic states with different resistances. Recently, it has been proposed that using a ferroelectric material as a barrier in MTJs will add new functionality and lead to new device concept. For example, this type of multiferroic tunnel junction will be a quaternary-state instead of a binary state device, which can potentially be useful in quantum information processing and multifunctional spintronic devices. We have recently studied tunnel junctions using ferromagnetic La0.7Ca0.3MnO3 and La0.7Sr0.3MnO3 as the electrodes and ferroelectric (Ba, Sr)TiO3 as the barrier in epitaxial trilayer structures. We show the junction has four stable resistance states with large differences of resistance among the states at zero applied magnetic and electric field. The states can be manipulated by combined electric and magnetic fields. In addition, we have found that the resistance/magnetic state of the junction can be switched both from the parallel to antiparallel state and the antiparallel to parallel state in certain but different field ranges by a voltage pulse. The switching does not depend on the polarity of the electrical field direction. The details of the switching voltage as a function of magnetic field and the implication of the magnetic state controlled by an electric field in spintronics will be discussed.
Prof. Qi Li 简介：
Qi Li is a professor of Physics at Pennsylvania State University. She joined Penn State as an assistance professor in 1995 and became a full professor in 2004. Her current research interest is primarily in the areas of spintronics and magnetic nanostructures, multiband superconductivity, and multiferroic materials and structures. She is the recipient of NSF Career award among others and a fellow of APS.
时间：2010年8月25日（星期三）下午2：30
地点：中科院物理研究所B楼二段404会议室
联系人：金奎娟 研究员 （Tel：82648099）
主办单位：中国科学院光物理重点实验室
