EXAFS as a probe for understanding magnetism in Heusler Alloys

Understanding the coupling between local atomic structure and magnetism is central to the design of functional materials used in spintronics, memory devices, and related technologies. Traditionally, X-ray scattering probes electronic charge density, and diffraction has served as the primary method for identifying crystallographic symmetry, phase transitions, and long-range order. However, the microscopic origins of magnetic interactions such as exchange pathways, hybridization strength, antisite disorder, and short-range structural distortions, often lie beyond the reach of diffraction – based techniques. Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy overcomes these limitations by providing element – specific access to local structural parameters through analysis of nearest neighbour environments.

In this talk, I will illustrate the power of EXAFS in studying functional magnetic materials, drawing on selected research contributions from our group. These examples demonstrate how EXAFS reveals subtle local features that remain hidden from conventional X-ray scattering, yet are crucial for understanding magnetic phenomena including martensitic ferromagnetism, re-entrant cluster-glass states, and the tuning of magnetic transition temperatures. A brief primer on EXAFS methodology and instrumentation will also be included.

Collectively, our work shows that when EXAFS is integrated with electronic transport and magnetic measurements, it provides a comprehensive and coherent picture of how local atomic structure governs magnetic behaviour. This combined approach not only deepens our understanding of contemporary magnetic materials but also offers valuable guidelines for designing next-generation functional magnetic materials.