Ultrafast magnetism as seen by x-rays

TY - GEN

T1 - Ultrafast magnetism as seen by x-rays

AU - Radu, Ilie

AU - Vahaplar, Kadir

AU - Stamm, Christian

AU - Kachel, Torsten

AU - Pontius, Niko

AU - Radu, Florin

AU - Abrudan, Radu

AU - Dürr, Hermann

AU - Ostler, Thomas

AU - Barker, Joe

AU - Evans, Richard

AU - Chantrell, Roy

AU - Tsukamoto, Arata

AU - Itoh, Akiyoshi

AU - Kirilyuk, Andrei

AU - Rasing, Theo

AU - Kimel, Alexey

AU - Evans, Richard Francis Llewelyn

PY - 2012/3/23

Y1 - 2012/3/23

N2 - Revealing the ultimate speed limit at which magnetic order can be controlled, is a fundamental challenge of modern magnetism having far reaching implications for magnetic recording industry. Exchange interaction is the strongest force in magnetism, being responsible for ferromagnetic or antiferromagnetic spin order. How do spins react after being optically perturbed on an ultrashort timescales pertinent to the characteristic time of the exchange interaction? Here we demonstrate that femtosecond measurements of X-ray magnetic circular dichroism provide revolutionary new insights into the problem of ultrafast magnetism. In particular, we show that upon femtosecond optical excitation the ultrafast spin reversal of Gd(FeCo) - a material with antiferromagnetic coupling of spins - occurs via a transient ferromagnetic state. The latter one emerges due to different dynamics of Gd and Fe magnetic moments: Gd switches within 1.5 ps while it takes only 300 fs for Fe. Thus, by using a single fs laser pulse one can force the spin system to evolve via an energetically unfavorable way and temporary switch from an antiferromagnetic to ferromagnetic type of ordering. These observations supported by atomistic simulations, present a novel concept of manipulating magnetic order on different classes of magnetic materials on timescales of the exchange interaction.

AB - Revealing the ultimate speed limit at which magnetic order can be controlled, is a fundamental challenge of modern magnetism having far reaching implications for magnetic recording industry. Exchange interaction is the strongest force in magnetism, being responsible for ferromagnetic or antiferromagnetic spin order. How do spins react after being optically perturbed on an ultrashort timescales pertinent to the characteristic time of the exchange interaction? Here we demonstrate that femtosecond measurements of X-ray magnetic circular dichroism provide revolutionary new insights into the problem of ultrafast magnetism. In particular, we show that upon femtosecond optical excitation the ultrafast spin reversal of Gd(FeCo) - a material with antiferromagnetic coupling of spins - occurs via a transient ferromagnetic state. The latter one emerges due to different dynamics of Gd and Fe magnetic moments: Gd switches within 1.5 ps while it takes only 300 fs for Fe. Thus, by using a single fs laser pulse one can force the spin system to evolve via an energetically unfavorable way and temporary switch from an antiferromagnetic to ferromagnetic type of ordering. These observations supported by atomistic simulations, present a novel concept of manipulating magnetic order on different classes of magnetic materials on timescales of the exchange interaction.

KW - Exchange interaction

KW - Ultrafast magnetization switching

KW - X-ray Magnetic Circular Dichroism

UR - http://www.scopus.com/inward/record.url?scp=84858610957&partnerID=8YFLogxK

U2 - 10.1117/12.907433

DO - 10.1117/12.907433

M3 - Conference contribution

AN - SCOPUS:84858610957

SN - 9780819489036

VL - 8260

BT - Proceedings of SPIE - The International Society for Optical Engineering

T2 - Ultrafast Phenomena and Nanophotonics XVI

Y2 - 22 January 2012 through 25 January 2012

ER -