Magnetic resonant holography

Cobalt/palladium multilayers present magnetic domains, with opposite polarizations perpendicular to the surface, that can be prepared in a disordered maze state. The electron density of the system is uniform, but the magnetic structure can be investigated by photon scattering, which depends on light polarization.

Müller et al., Synchrotron Radiation News 26, 27–32 (2013).

Magnetic resonant hologram of Co/Pd domains

The coherent pulses of the FERMI@Elettra seeded FEL can be tuned at the Co M-edge to enhance the sample magnetic photon scattering, that can be detected on a CCD as a ring, with a characteristic radius determined by the domains' average size.

Imaging of the magnetic structure can be achieved through holography, irradiating the sample with circularly polarized light, through a deposited gold mask with a circular 2 μm sample area surrounded by 5 reference holes of 80 or 60 nm, and irradiating the sample with resonant photons. Taking the difference between diffraction patterns acquired with left and right circular polarizations, dichroic effects are enhanced and 10 images of the magnetic domains can be obtained, as the convolution between the sample circular area and each reference dot, with a single Fourier transform.

Thanks to the intensity and spectral stability of FERMI@Elettra, the experiment can be carried out in integration mode without destroying the sample. The ultrafast FEL pulses have also been coupled with the infrared seed, used as a pump source for a femtosecond time resolved experiment, to observe with holography the fast demagnetization induced by the infrared pump.

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Magnetic domain structures seen by coherent Free-Electron Laser light.

L. Müller, S. Schleitzer, C. Gutt, B. Pfau, J. Geilhufe, F.Büttner, C. von Kor Schmising, S. Scha ert, F. Capotondi, E. Pedersoli, S. Düsterer, H. Redlin, A. Al-Shemmary, R. Treusch, J. Bach, R. Frömter, B. Vodungbo, J. Lüning, H.-P. Oepen, M. Kiskinova, S. Eisebitt, G. Grübel.

Synchrotron Radiation News 26, 27–32 (2013).

DOI: 10.1080/08940886.2013.850384

Last Updated on Monday, 21 December 2015 10:58