I. Ultrafast Magnetization Dynamics on the Nanoscale

Temporal spin behavior in magnetic systems at short length and time scales

  • Time and length scales in magnetism
  • Magnetically sensitive X-ray measurement techniques
  • Ultrafast manipulation of the magnetization
  • Instabilities in low-dimensional magnetism
Magnetism is responsible for one of the oldest inventions, the magnetic compass, and further applications have revolutionized our world, through, e.g., ferrite core memor y to today’s high-density data storage. In modern magnetic storage devices, of the order of 400 gigabits can be written per square inch at a rate of one bit per two nanoseconds. Faster reversal, on the sub-ps time scale, has been demonstrated, but its origins still remain to be investigated. The fact that many fundamental magnetic processes take place on the nanometer length and picosecond time scales, and the high magnetic sensitivity of resonant, circularly-polarized X-rays, make the SwissFEL a versatile instrument for state-of-the-ar t research in magnetism. Of par ticular current interest are the ultrafast disappearance, creation and modification of magnetic order and the novel quantum effects which arise in two-, one- and zero-dimensional systems. The Swiss- FEL, with coherent, high-brightness, circularly-polarized X-rays at energies resonant with the 3d-transition metal ions, corresponding to nm wavelengths, is capable of single-shot lensless imaging of nanometer-scale magnetic structures. Fur thermore, the combination of high-energy, half-cycle THz pump pulses and the synchronized, sub-picosecond SwissFEL probe pulses will permit the investigation in real time of ultrafast magnetic interactions.