Obtaining soft x-ray constants across the 2p edge of Fe in thin films by resonant magnetic scattering experiments of polarized soft X-rays Fabian Walter, H.-Ch. Mertins, Andreas Gaupp, Franz Schäfers, Wolfgang Gudat

Synchrotron Radiation BESSY II Synchrotron radiation as a light source. Radiation is produced by electrons radiating to due centripetal acceleration when following a circular path of about 240m circumference near the speed of light (Peatman) Advantages: Strong bundled light beam Strong bundled light beam Polarization and intensity can be precisely calculated Polarization and intensity can be precisely calculated Coherence and time structure Coherence and time structure High intensity of the light beam High intensity of the light beam Continuous spectrum (Peatman) Continuous spectrum (Peatman)Undulators Tuneable and known polarisation and intensity Tuneable and known polarisation and intensity Polarisation of emitted light can thus be controlled to have circular and linear components (Weiss, Sahwney) Polarisation of emitted light can thus be controlled to have circular and linear components (Weiss, Sahwney)

Undulator Radiation Gap and shift Gap and shift

Application Using synchrotron radiation for reflection and transmission measurements Magnetooptical effects Example: Determining optical constants for magnetic materials such as Fe Optical constants are not certainly known for many materials in the VUV Optical constants are not certainly known for many materials in the VUV Needed for manufacturing of computational devices Needed for manufacturing of computational devices Knowledge of polarization of the incoming light beam enlarges possibilities Knowledge of polarization of the incoming light beam enlarges possibilities

Magnetooptical Kerr-Effect (MOKE) L-MOKE  22   B  T-MOKE  22 B B  P-MOKE  22

Magnetic Dichroism

BESSY Soft X-Ray Polarimeter

Fit curves for L-Moke

Magnetic Dichroism

Fit curves for L-Moke

Asymetry in L-MOKE

Fit curves in T-MOKE

Asymetry in T-MOKE

Results for non-magnetic terms

Results for magnetic terms

Comparison with other experiments

Conclusion Exploiting tuneable synchrotron radiation Obtaining optical constants for Fe New technique for obtaining optical constants in the soft x-ray regime for other materials such as Co, Ni, Gd