Radboud University

报告人简介：

Theo Rasing is professor of physics at Radboud University, Nijmegen, the Netherlands, member of the Royal Dutch Academy of Arts and Sciences and Academia Europaea, honorary professor Wuhan University of Technology, honorary member Ioffe Institute in St. Petersburg, recipient ERC Synergy Grant 2019, ERC Advanced Grant 2013, Prize for Science and Society 2008 and Spinoza Award 2008, the highest scientific award of the Netherlands. He has co-authored over 500 papers (h= 83, GS), including 44 Physical Review Letters and 19 in Nature Group journals that were cited over 32000 times and is co-inventor on 4 patent applications. A Physical Review Letters of 2007 was mentioned as a Breakthrough of the year by Science.

报告摘要：

Since our demonstration of magnetization reversal by a single 40 femtosecond laser pulse, the manipulation of spins by ultra-short laser pulses has developed into an alternative and energy efficient approach to magnetic recording. Though originally thought to be due to an optically induced effective magnetic field, later studies demonstrated that the switching occurred via a strongly non-equilibrium state, exploiting the exchange interaction between the spins. Recent work also show how magnetic textures like skyrmions are generated via a strongly non-equilibrium phase.

While for a long time, all-optical switching (AOS) was exclusively observed in ferrimagnetic alloys, more recent work demonstrated AOS in a broad range of ferromagnetic multilayer materials, albeit that in those examples a large number of pulses were required. By studying the dynamics of this switching process, we have discovered that this switching is a 2-step process of nucleation and switching, which has led to the subsequent demonstration that highly efficient AOS can be achieved by using pairs of femto/pico-second laser pulses, that are separated by a precisely tuned delay time. By combining optical laser excitation with in situ magnetic force microscopy, we recently found that the nucleation and switching process evolves via a stochastic network of domains.

邀请人：成昭华（8264 8083）

联系人：胡  颖（8264 9361）