A high-energy inelastic neutron scattering investigation of the Gd-Co exchange interactions in Gd Co 4 B : Comparison with density-functional calculations

• Published in: Journal of applied physics 2008-07, Vol.104 (1), p.013922-013922-6
• Main Authors: Isnard, Olivier, Kuz'min, Michael D., Richter, Manuel, Loewenhaupt, Michael, Bewley, Robert
• Format: Article
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/1.2953099

Inelastic neutron scattering is used to quantify the Gd-Co exchange interaction in Gd Co 4 B . A significant reduction is observed in comparison with the Gd Co 5 compound. A mean value of 130 T is obtained for the exchange field on the two Gd sites in Gd Co 4 B . The experimental results are compared with density-functional calculations. The local atomic magnetic moments calculated using the LSDA + U approximation are reported for each atomic site of the Gd Co 4 B crystal structure. These calculations demonstrate that the two nonequivalent Gd crystal sites experience a significantly different exchange interaction, a difference that is discussed in the light of the local atomic environment. The observed reduction of the exchange field occurring upon substituting B for Co in Gd Co 5 is mainly caused by the decrease of the Co magnetic moment, whereas the Gd-Co coupling constant is found to be almost the same in both Gd Co 5 and Gd Co 4 B .