First-principles study of Dzyaloshinskii-Moriya Interaction

admin   2018-10-15 12:41:54   3474

报告题目:First-principles study of Dzyaloshinskii-Moriya Interaction
报告时间:2018-10-22 09:00 (星期一)
报告地点:32教学楼B218
报告人:杨洪新 研究员 (宁波材料所)

联系人:米文博    Email:miwenbo@tju.edu.cn 

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First-principles study of Dzyaloshinskii-MoriyaInteraction 

杨洪新中国科学院磁性材料与器件重点实验室,中科院宁波材料技术与工程研究所         

TheDzyaloshinskii-Moriya Interaction (DMI) between spins induced by spin-orbitcoupling (SOC) in magnetic materials lacking inversion symmetry and in particularat the interface between ferromagnetic (FM) and heavy nonmagnetic (NM) metalshas become recently a subject of tremendous interest for both fundamentalresearch and applications. This is because the DMI is recognized to play themost prominent role for creating topologically non-trivial textures calledmagnetic Skyrmion which is very attractive for ultra-dense information storageand spintronic devices. Furthermore, DMI plays an essential role for fastdomain wall (DW) dynamics driven by spin-orbit torques. It has been shown thatthe DW velocity strongly depends on the relative parameters of exchangecoupling, magnetic anisotropy and the DMI. Thus, much attention has been paidon searching efficient material combinations giving rise to large DMI values atFM/NM interfaces. Ourrecent study of DMI at Co/Pt interfaces [1] has unveiled the main features andmicroscopic mechanisms of DMI in FM/NM bilayers. We found that the largeanticlockwise (ACW) DMI of the Co/Pt bilayers has a predominant contribution frompair couplings between the spins of the interfacial Co layer. This DMI betweenthe interface Co spins is directly related to the change of the SOC energy inthe interface Pt atoms, demonstrating the picture of Fert-Levy type interfacialDMI from first-principles.Basedon the understanding of the DMI mechanism at FM/NM interfaces [1], we proposeseveral approaches to control the DMI in ultrathin magnetic films and enhanceits amplitude. First, the DMI can be enlarged via multilayer stacking of FM andNM metals possessing the required DMI chiralities in corresponding FM/NMbilayers. Next approach is adding an oxidized capping layer, such as MgO, ontop of a Co/Pt bilayer. We show that the DMI in MgO/Co/Pt is much larger, about1.6 times, compared to that in Co/Pt bilayers for all the Co thicknessesconsidered. [2] Moreover, we explore the possibility of electric field controlof DMI in Oxide/FM/NM structures. [3] Lastly,I’ll also report the Rashba effect induced interfacial Dzyaloshinskii-MoriyaInteraction at graphene/FM interfaces, which is beyond Fert-Levy type DMI, openinga route creating Skyrmions without heavy metals[4].   

[1] H. X. Yang, et al. Physical Review Letters 115, 267210(2015). 

[2] O. Boulle, H. X.Yang et al. Nature Nanotech. 11, 449-454 (2016) 

[3] H Yang, O Boulle,V Cros, A Fert, M Chshiev, arXiv preprint arXiv:1603.01847 

[4] H. Yang, G.Chen, A. A.C. Cotta, A. T. N'Diaye, S. A. Nikolaev, E. A. Soares, W. A. A.Macedo, A. K. Schmid, A. Fert, M. Chshiev, Nature Materials 17,604(2018)   


报告人简介:   

杨洪新 研究员 杨洪新,中国科学院宁波材料技术与工程研究所研究员,博士生导师,中国科学院磁性材料与器件重点实验室副主任。本科毕业于吉林大学,硕士在吉林大学和中科院物理所联合培养,2012年于法国格勒诺布尔大学获得博士学位,后陆续在巴黎十一大,澳大利亚联邦科学与工业研究中心(CSIRO),SPINTEC,法国国家科学中心和泰雷兹联合物理实验室,以及日本国立材料研究所(NIMS)从事科学研究工作,2017年5月加入宁波材料所。  研究兴趣主要集中在表面界面自旋电子学的理论计算研究,已在Nature Materials,Nature Nanotech.,Phys. Rev. Lett.,Nano Letters,Advanced Materials等杂志上发表论文40余篇,在铁磁金属与氧化物界面自旋电子学,5d和3d金属界面的自旋轨道电子学,自旋霍尔效应以及石墨烯自旋电子学等领域都有文章入选ESI高引用论文。 Email: hongxin.yang@nimte.ac.cn


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