Investigation of AlFe2B2 single crystals by XANES and XMCD

AlFe2B2 is a nano-layered boride which exhibits a strong magneto-caloric effect (MCE) as well as a room temperature ferromagnetic to paramagnetic transition. This compound has attracted a lot of interest regarding its potential application for magnetic refrigeration. Its MCE happens to be of the same order as Gd5Si2Ge2 and other magneto-caloric compounds, while being a rare earth free material made of lights and abundant elements. It has been demonstrated that the curie temperature of AlFe2B2 should strongly diminish with pressure. A relationship between the magnetic transition and magnetostructural couplings or magnetoelastic effects have also been hinted at. Following those very recent studies, we will investigate the local electronic and magnetic environment and structure of the magnetic Fe atom in AlFe2B2 as a function of pressure and temperature, using high pressure XANES and XMCD at the Fe K edge. This will help shed light on the microscopic origins on the MCE in this phase.