Shining Soft X-rays on Magnetic Structures

Abstract

The study of magnetic materials with x-rays is developing at a breathtaking pace. The methods used in these studies extend magneto-optics—the response of a material to optical excitation as a function of the relative orientation of magnetization and light polarization—to the x-ray regime. One of the key advantages of these techniques is that they are element specific, because the photon wavelength (or energy) in the x-ray regime can be tuned to match the excitation energy of a discrete core electronic level. Also, layer thicknesses of magnetic multilayers and lateral structures in novel magnetic devices that are presently being developed are comparable to soft x-ray wavelengths. Therefore, detailed insight into the magnetic properties of these technologically important magnetic structures can be obtained by use of soft x-rays. The soft x-ray regime is of importance because all technically relevant magnetic materials contain 3d transition metals, for which the 2p excitation that shows the highest sensitivity to the magnetic state lies between 500 and 1000 eV.