题目1： Magneto-dynamics in Spin Hall Nano-Oscillators

报告人：Dr. Philipp Dürrenfeld

时间：2016年03月17日（周四）下午14:00

地点：比较靠谱的赌博大平台九龙湖校区田家炳楼南203

简历：Dr. Philipp Dürrenfeld  received the diploma degree in Nanostructure Engineering and the Ph.D. degree in Natural Science Specialising in Physics from the University of Würzburg (Germany) in 2010 and Department of Physics, University of Gothenburg(Sweden)  in 2015, respectively. He then joined the Department of Physics, University of Gothenburg(Sweden) as the temporary postdoc and research assistant in applied spintronics. Now Dr. Philipp Dürrenfeld moved to the School of Electronic Science & Engineering, Nanjing University (China), where he is recommended to set up microwave detection apparatus for the spin-torque oscillators and develope the research center in SHE oscillators as Postdoctoral researcher. His areas of interests magnetic materials with a focus on magnetic microstructures and devices by Ferromagnetic Resonance. He has published 23 technical articles in peer-reviewed journals, including Nature Nanotech., Phys. Rev. B, Appl. Phys. Lett., IEEE Magn. Lett. and so on. He has also presented 11 of his research results 

摘要: Spin-torque oscillators (STOs) are capable of producing tunable broadband high-frequency signals within a nanometer-sized region. Recently, STOs that make use of pure spin currents, generated by the spin Hall effect (SHE), have become promising candidates for pure spin-wave based logics, since no charge current flow through the magnetic material is required, in contrast to conventional spin-valve-based STOs. The SHE establishes a spin accumulation in materials with strong spin orbit coupling, e.g., Platinum. A spin transfer torque is then acted upon an adjacent magnetic layer due to the spin accumulation and its accompanying pure spin current flow. Here, recent developments in SHE-driven auto-oscillations will be presented, which have been studied in a wide range of materials, in different device geometries, and in several external field conditions, leading to a variety of magneto-dynamic modes.

题目2 (归国汇报)：Tunable magneto-dynamic properties of alloyed permalloy films

报告人：Yuli Yin（尹玉莉）

摘要：Investigations of the magneto-dynamic properties of magnetic films have attracted widespread interest. In particular the excitation of perpendicular standing spin waves (PSSWs) prove to be particularly useful. PSSWs have a short wavelength, are exchange-dominated, and their wave vector points perpendicular to the film surface. Furthermore, alloyed permalloy (Py) films are excellent candidates for high-frequency operation in spintronic devices, such as in nano-contact spin-torque oscillators (NC-STOs) , as the output characteristics of such devices are governed by the magnetic properties of the free layer. Here we show that the intrinsic magneto-dynamical parameters of doped Py films, such as the saturation magnetization (M_S), damping (α), and exchange stiffness (A) can be tuned by selectively alloying with different heavy metals. These parameters are of critical importance for the excitation of exchange dominated (or mixed dipole exchange) spin wave modes in NC-STOs since they directly influence the critical current I_crit, spin wave propagation length  and frequency.