Ab initioexchange interactions and magnetic properties of theGd2Fe17iron 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 Gd 2 Fe 17 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 sphereexchange 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 T C for the first as well as for the first and second coordination spheres of both hexagonal and rhombohedral phases of Gd 2 Fe 17 within Weiss mean-field theory were estimated. Obtained values of T C and its increase going from the hexagonal to rhombohedral crystal structure of Gd 2 Fe 17 agree well with experiment. Also for both structures LSDA+ U computed values of total magnetic moment agree well with experimental ones.

Experimental and theoretical study of magnetic ordering and local atomic polarization in Ru-substitutedLu2Fe17

“…Furthermore, we find that all pair-wise exchange interactions in the ideal Lu 2 Fe 16.5 Ru 0.5 crystal are positive, with the strongest exchange in the 4f dumbbell Fe pairs of approximately 54 meV (cf. with 20.6 meV obtained theoretically for the same positions in the hexagonal, ferromagnetic Gd 2 Fe 17 [47]). The deviation of theoretical calculations from the experimentally observed spiral-spin configuration seemingly stems from simulating a perfect crystal, while experimental data are obtained on an off-stoichiometric compound with local structural defects.…”

Magnetic properties and exchange interactions in TbNi5−xMx (M=Co and Fe) compounds: Ab initio calculations

“…In Ref. 8 it was demonstrated that the Curie temperature values can be estimated from the calculated LEIP parameters in the 3d sublattice only. However, in the first coordination sphere one finds the largest values of the exchange interaction with the nearest neighbors that determine the order of T C .…”

Effect of copper and cobalt impurities on the electronic structure and optical spectra of the intermetallic compound PrNi5

“…Conversely, the substitution of magnetic cobalt ions for nickel ions resulted in an increase of the total magnetic moment to 4.2 μ B in PrNi 4 Co and to 5.3 μ B in PrNi 3 Co 2 . The appearance of magnetic moments of the cobalt ions in the 3d sublattice of PrNi 5 leads to an enhancement of the exchange interactions, which contributes to the increase of the Curie temperature [18,19].…”