Magnetic X-ray Scattering: Some Deliberate and Some Accidental Observations of X-ray Birefringence
I will outline some recent experiments in x-ray birefringence, including dynamic imaging of molecular polarization. Birefringence allows very strong coupling to circular polarization. I will show that this is a strong enough effect to exploit as a circular polarimeter.
Moreover, birefringence must be taken into account when analysing resonant scattering data in order to avoid misinterpreting circular dichroism in resonant magnetic scattering, for example. In the second part of the talk I will describe some recent experiments to determine the sign of the Dzyaloshinskii-Moriya vector in globally centro-symmetric crystals by exploiting magnetic/resonant quadrupole interference to determine the phase of the magnetic scattering amplitude. I will also take the opportunity to highlight the capabilities of Diamond Beamline I16: Materials & Magnetism.