Lecture A.V. Kimel
|03 december 2007||FWN-Building 5118.-152, Nijenborgh 4, 9747 AG, Groningen|
|Speaker:||Dr. A.V. Kimel|
|Affiliation:||IMM, Radboud University Nijmegen|
|Date:||Mon Dec 3, 2007|
|Host:||Paul van Loosdrecht|
|Telephone:||+31 50 363 8149|
The demand for the ever-increasing speed of information storage and manipulation has triggered an intense search for ways to control the magnetization of a medium by means other than magnetic fields. The control of magnetism by light is one of the promising approaches to this problem, because such methods may access timescales of a picosecond (10-12 sec) or less .
Can light directly and nonthermally magnetize a medium? A circularly polarized photon carries angular momentum. If it would be possible, using this angular momentum, to affect spins of electrons directly, this would result in ultrafast laser control of magnetism, since right- and left-handed circularly polarized light-waves should affect spins as magnetic fields of opposite sign. Recently, our group observed for the first time ultrafast and nonthermal effects of light on magnetization . We demonstrated that circularly polarized 100-femtosecond (10-13 seconds) laser pulses can excite and coherently control the spins in magnets. Moreover, the effect of this ultrashort optical pulse on a magnetic system was found to be equivalent to the effect of an equally short magnetic field pulse with strengths up to 1 T. Therefore, in contrast to the well-known magneto-optical Faraday effect, where the polarization of light is affected by magnetism, these experiments demonstrate the feasibility of the inverse, opto-magnetic phenomenon: polarized light affects magnetism via the inverse Faraday effect.
In my lecture I will discuss fundamental aspects of interaction between photons and spins, magneto-optical and opto-magnetic phenomena, microscopical mechanisms responsible for laser control of magnetism. Our recent experiments on laser excitation of magnetic resonances, quantum control of magnons, ultrafast phase transitions and femtosecond laser-induced switching of magnetization [3-6] will be reviewed.
[ 1] A. V. Kimel et al, Nature 429 850 (2004)
 A. V. Kimel et al., Nature 435 655 (2005).
 A. V. Kimel et al., J. Phys. Cond. Mat. 19 043201 (2007).
 C. D. Stanciu et al, Phys. Rev Lett. 99 047601 (2007).
 C. D. Stanciu et al., Patent PCT/NL2006/000264.
 A. M. Kalas hnikova et al., Phys. Rev Lett. 99, 167205 (2007).
|Laatst gewijzigd:||22 oktober 2012 14:31|