%0 Electronic Article
%A Schmitt, Annika
%A Joly, Yves
%A Schulze, Kai Sven
%A Marx-Glowna, Berit
%A Uschmann, Ingo
%A Grabiger, Benjamin
%A Bernhardt, Hendrik
%A Loetzsch, Robert
%A Juhin, Amelie
%A Debray, Jérôme
%A Wille, Hans-Christian
%A Yavas, Hasan
%A Paulus, Gerhard
%A Röhlsberger, Ralf
%T Disentangling X-ray dichroism and birefringence via high-purity polarimetry
%J Optica
%@ 2334-2536
%C Washington, DC
%I OSA
%M PUBDB-2020-04918
%P 1-10
%D 2020
%Z 6 pages, 4 figures, 8 pages supplemental material (4 figures)
%X The advent of high-brilliance synchrotron radiation sources has opened new avenues for X-ray polarization analysis that go far beyond conventional polarimetry in the optical domain. With linear X-ray polarizers in a crossed setting remarkable polarization extinction ratios down to 10<sup>−10</sup> can be achieved. This renders the method sensitive to probe tiniest optical anisotropies that would occur, for example, in strong-field QED due to vacuum birefringence and dichroism. Here we show that high-purity polarimetry can be employed to reveal electronic anisotropies in condensed matter systems with utmost sensitivity and spectral resolution. Taking CuO and La<sub>2</sub>CuO<sub>4</sub> as benchmark systems, we present a full characterization of the polarization changes across the Cu K-absorption edge and their separation into dichroic and birefringent contributions, supported by calculations via an ab-initio quantum code. Our results not only pave the way for the precision detection of symmetry breaking interactions in correlated materials. At the upcoming diffraction-limited synchrotron radiation sources and X-ray lasers, where polarization extinction ratios of 10<sup>−12</sup> can be achieved, our method has the potential to assess birefringence and dichroism of the quantum vacuum in fundamental studies of extreme electromagnetic fields.
%F PUB:(DE-HGF)25
%9 Preprint
%R 10.3204/PUBDB-2020-04918
%U https://bib-pubdb1.desy.de/record/452903