Soft-x-ray Faraday rotation at FeL2,3edges

Abstract

We measured Faraday rotation of linearly polarized soft x rays across the Fe ${\mathit{L}}_{2,3}$ edges transmitted through an Fe/Cr multilayer in an applied magnetic field; the maximum rotation of 6×${10}^4$ deg/mm is larger than that observed for Fe in other spectral regions. Rotation data agree well with Kramers-Kronig analysis of absorption data measured using left and right circular polarization. A tunable elliptically polarizing undulator source provided linearly and circularly polarized x-ray beams. The tunable multilayer polarizer used extends optical rotation techniques into the 50–900-eV region, with element specificity from core resonances.