Magnetic spectroscopy at high pressures using X-ray magnetic circular dichroism

The imbalance in the electronic density of states between spin-up and spin-down electrons characteristic of ferro(ferri)-magnetic materials gives rise to X-ray magnetic circular dichroism (XMCD) in the absorption of circularly polarized X-rays with opposite helicity. These dichroic effects are largest near element-selective atomic resonances and can be used to probe ferro(ferri)-magnetic ordering with element- and electronic orbital-selectivity. We describe recent developments at the Advanced Photon Source that allow measurements of XMCD in a diamond anvil cell. We discuss the challenges associated with these measurements as well as their potential to further our understanding of complex magnetic materials.