12 April 2013

COBRA COLLOQUIUM: Friday April 12, 2013 at 15:00 – 16:00 in the Film Theater of Grand Café and Film house De Zwarte Doos

Speaker: Prof. Dr. Theo Rasing

Title: Controlling Magnetism by Light

Abstract: From the discovery of sub-picosecond demagnetization over a decade ago to the recent demonstration of magnetization reversal by a single 40 femtosecond laser pulse, the manipulation of spins by ultra short laser pulses has become a fundamentally challenging topic with a potentially high impact for future spintronics, data storage and manipulation and quantum computation. In addition, when the time-scale of the perturbation approaches the characteristic time of the exchange interaction (~10-100 fs), the magnetization dynamics enters a novel, highly non-equilibrium, regime, which was recently demonstrated by both fs optical and X-ray experiments. Theoretically, this field is still in its infancy, using phenomenological descriptions of the none-equilibrium dynamics between electrons, spins and phonons. A proper description should include the time dependence of the exchange interaction and nucleation phenomena on the nanometer length scale. Such developments need to be supported by experimental investigations of magnetism at its fundamental time and length scales, i.e. with fs time and nanometer spatial resolution. Using ultrashort optical excitations, we may be able to manipulate the exchange interaction itself. In this lecture recent results and future challenges of ultrafast magnetization dynamics and the opto-magnetic techniques to control magnetic order will be discussed. 
Recent references:
A. Kirilyuk, et al, Rev. Mod. Phys. 82, 2731-2784 (2010)
I. Radu et al, Nature 472, 205 (2011)
J. Mentink et al, Phys.Rev.Lett. 108, 057202 (2012)
T. Ostler et al, Nature Comm. 3, 666 (2012)
A.R. Khorsand et al, Phys.Rev.Lett.108, 127205 (2012)
C. Graves et al, Nature Materials, to appear (2013)

Demonstration of magnetic domain switching by unpolarized laser pulses (T.Ostler et al)

Biography: Theo Rasing (1953) is professor experimental physics, an elected member of the Royal Dutch Academy of Arts and Sciences (KNAW), Knight of the Order of the Dutch Lion and founder and Director of the Nijmegen Centre for Advanced Spectroscopy. In 2007 he received the Fysica prize and in 2008 the NWO Spinoza award, the highest scientific honour in the Netherlands for his work on the optical manipulation of magnetism.

After the colloquium (around 16:00) we organize a mini-colloquium in which three COBRA researchers, one from each of the three COBRA groups, will give a short presentation about his or her work.

For the Photonic Integration Group:
Speaker: Emil Kleijn Title: Low Reflection Multimode Interference couplers
For the Photonics and Semiconductor Nanophysics Group:
Speaker: Leonardo Midolo Title: Controlling the spontaneous emission of single quantum dots with nano-electromechanical photonic crystals For the Electro Optical Communication Group:
Speaker: Yan Shi Title: Broadband In-Home Communication using Plastic Optical Fibre

The audience is invited to an informal gathering following the colloquium in the lounge of Grand Café and Film house De Zwarte Doos

The next COBRA Colloquium will take place on Friday, May 17, 2013 
Location: TU/e, the Film Theater of Grand Café and Film house De Zwarte Doos
Time: 15:00 hours