Ab Initio Exchange Interactions and Magnetic Properties of the Gd2 Fe17 Iron Sublattice: Rhombohedral Versus Hexagonal Phases

Abstract

In the framework of the local spin-density approximation LSDA+U method electronic-structure and magnetic properties of the intermetallic compound Gd2 Fe17 for both rhombohedral and hexagonal phases have been calculated. On top of that, ab initio exchange-interaction parameters within the Fe sublattice for all present nearest and next-nearest Fe ions have been obtained. It was found that for the first coordination sphere-exchange interaction is ferromagnetic. For the second coordination sphere-exchange interaction is observed to be weaker and of antiferromagnetic type. Employing the theoretical values of exchange parameters Curie temperatures TC for the first as well as for the first and second coordination spheres of both hexagonal and rhombohedral phases of Gd2 Fe17 within Weiss mean-field theory were estimated. Obtained values of TC and its increase going from the hexagonal to rhombohedral crystal structure of Gd2 Fe17 agree well with experiment. Also for both structures LSDA+U computed values of total magnetic moment agree well with experimental ones. © 2009 The American Physical Society.