Letter

Nature 435, 655-657 (2 June 2005) | doi:10.1038/nature03564; Received 25 November 2004; Accepted 15 March 2005; Published online 25 May 2005

Ultrafast non-thermal control of magnetization by instantaneous photomagnetic pulses

A. V. Kimel1, A. Kirilyuk1, P. A. Usachev2, R. V. Pisarev2, A. M. Balbashov3 & Th. Rasing1

  1. IMM, Radboud University Nijmegen, 6525 ED Nijmegen, The Netherlands
  2. Ioffe Physico-Technical Institute, 194021 St Petersburg, Russia
  3. Moscow Power Engineering Institute, 111250 Moscow, Russia

Correspondence to: Th. Rasing1 Correspondence and requests for materials should be addressed to T.R. (Email: th.rasing@science.ru.nl).

The demand for ever-increasing density of information storage and speed of manipulation has triggered an intense search for ways to control the magnetization of a medium by means other than magnetic fields1, 2, 3, 4, 5. Recent experiments on laser-induced demagnetization6, 7, 8 and spin reorientation9 use ultrafast lasers as a means to manipulate magnetization, accessing timescales of a picosecond or less. However, in all these cases the observed magnetic excitation is the result of optical absorption followed by a rapid temperature increase. This thermal origin of spin excitation considerably limits potential applications because the repetition frequency is limited by the cooling time10. Here we demonstrate that circularly polarized femtosecond laser pulses can be used to non-thermally excite and coherently control the spin dynamics in magnets by way of the inverse Faraday effect. Such a photomagnetic interaction is instantaneous and is limited in time by the pulse width (approx200 fs in our experiment). Our finding thus reveals an alternative mechanism of ultrafast coherent spin control, and offers prospects for applications of ultrafast lasers in magnetic devices.