报告题目:Twisted magnon frequency comb and Penrose superradiance
报告摘要:
Quantization effects of the nonlinear magnon-vortex interaction in ferromagnetic nanodisks are studied. We show that the circular geometry twists the spin-wave fields with spiral phase dislocations carrying quantized orbital angular momentum (OAM). Meanwhile, the confluence and splitting scattering of twisted magnons off the gyrating vortex core (VC) generates a frequency comb consisting of discrete and equally spaced spectral lines, dubbed as twisted magnon frequency comb (tMFC). It is found that the mode spacing of the tMFC is equal to the gyration frequency of the VC and the OAM quantum numbers between adjacent spectral lines differ by one. By applying a magnetic field perpendicular to the plane of a thick nanodisk, we observe a magnonic Penrose superradiance inside the cone vortex state, which mimics the amplification of waves scattered from a rotating black hole. It is demonstrated that the higher-order modes of tMFC are significantly amplified while the lower-order ones are trapped within the VC gyrating orbit which manifests as the ergoregion. These results suggest a promising way to generate twisted magnons with large OAM and to drastically improve the flatness of the magnon comb.
个人简介:
严鹏,电子科技大学教授,博士生导师,2006年本科毕业于中国科技大学近代物理系,2011年于香港科技大学获得物理学博士学位。2011-2015年期间,先后在荷兰代尔夫特理工大学,德国美因兹大学从事博士后研究工作。2016年入选海外高层次人才,并组建电子科技大学自旋电子学理论研究组,主要研究领域为自旋电子学,拓扑磁动力学,以及量子自旋波电子学,担任物理学期刊Frontiers in Physics 副主编(Associate Editor)。已发表高水平研究成果60余篇,其中《物理评论快报》7篇,《物理评论》30篇,《纳米快报》2篇,受邀为物理学顶尖综述期刊《物理报道》撰写长篇综述两篇,受施普林格出版社邀请撰写专著一章,拥有十余项中国和美国发明专利。课题组主页链接:http://www.xtronics.com.cn