XMCD study of the first-order magnetization process in U3Cu4Ge4

U3Cu4Ge4 is a ferromagnet with the magnetic moments aligned along the [100] axis of the orthorhombic crystal structure. When magnetic field is applied along the hard [010] direction, U3Cu4Ge4 displays a firstorder phase transition in the magnetization at H* = 25 T. This phase transition occurs due to the existence of two inequivalent minima in the magnetic-anisotropy energy of the material and reflects a strong response of the 5f electrons. Our magnetization and ultrasound data strongly suggest a Fermi-surface reconstruction and lattice deformation at H*. Here, we propose to perform orbital-selective magnetometry through x-ray magnetic circular dichroism at the U L3 edge to determine the microscopic nature of the field-induced transition. Our goal is to analyze dipolar and quadrupolar contributions in the U L3 edge XMCD in order to resolve the degree of localization of the 5f electrons in U3Cu4Ge4.