Electronic structure of cage-like compound UFe₂AI₁₀ – Theory and XPS experiment

The U-Fe-Al system exhibits several ternary phases . Among the most intensively investigated phases are those with a generalized formula of UFexAl12-x, possessing a wide Fe-content range for 3<x<6. In this composition range four magnetic phase regions have been identified. All these phases crystallize in the tetragonal ThMn12-type structure. Interestingly that the considered here true stoichiometric phase, UFe2Al10, adopts a different structure of the orthorhombic YbFe2Al10-type with the Cmcm symmetry that is closely related to the ternary ordered-variant of the CeMn4Al8-type (I4/mmm symmetry). In the YbFe2Al10-type structure, the uranium atom has a coordination number (CN) of 20 (4Fe + 16 Al) while the iron atom forms in its coordination a distorted icosahedral having the 2 U and 10 Al atoms. Zenou et al. based on the total energy calculations, using the full potential band structure method with linearized augmented plane waves (FP-LAPW) with the spinorbit (SO) coupling correction, explained why the UFe2Al10 compound has rather the YbFe2Al10-type than ThMn12-type structure. In turn, as many as five different sites are occupied in the UFe2Al10 structure by the Al atoms. They coordinate in the irregular polyhedron of the U, Fe or Al atoms with CN ranging from 12 to 14