Spectroscopic Investigation of Earth Abundant Magnetocaloric AlFe2B2 Single Crystals

The rapid expansion of modern technologies necessitates parallel advances in energy efficiency and thermal management. Based on the magnetocaloric effect, magnetic refrigeration offers a solid-state pathway that circumvents the inefficiencies and environmental costs of conventional cooling [1]. Among candidate systems, AlFe₂B₂ has emerged as an earth-abundant material with a ferromagnetic transition at 280 K, ideally near ambient conditions [2]. Despite its promise, the electronic structure of the material has not been rigorously explored. Here, we present a comprehensive experimental study of single-crystal AlFe₂B₂ combining X-ray diffraction (XRD), angle-resolved photoemission spectroscopy (ARPES), and X-ray magnetic circular dichroism (XMCD), carried out at synchrotron facilities worldwide. Together, these probes provide access to the structural, electronic, and spin degrees of freedom across the transition. The data is compared to density functional theory (DFT) calculations to further clarify the electronic structure, bringing us closer to an understanding of the underlying mechanism of the magnetocaloric transition. These results advance the fundamental understanding of AlFe₂B₂ and establish a foundation for unraveling the physics of magnetocaloric transitions in related compounds.