A high-energy inelastic neutron scattering investigation of the Gd-Co exchange interactions in GdCo4B: Comparison with density-functional calculations

Olivier Isnard (1) , Michael D. Kuz'Min (2) , Manuel Richter (2) , Michael Loewenhaupt (2) , Robert Bewley (3)

1 NEEL - MRS - Matériaux, Rayonnements, Structure
2 IFW Dresden - Leibniz Institute for Solid State and Materials Research
3 ISIS - ​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​ISIS Neutron and Muon Source

Inelastic neutron scattering is used to quantify the Gd-Co exchange interaction in GdCo4B. A significant reduction is observed in comparison with the GdCo5 compound. A mean value of 130 T is obtained for the exchange field on the two Gd sites in GdCo4B. 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 GdCo4B 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 GdCo5 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 GdCo5 and GdCo4B.

Mots clés: Exchange and superexchange interactions; Saturation moments and magnetic susceptibilities; Other ferromagnetic metals and alloys; Chemical exchanges; Exchange interactions

Domaines: Science des matériaux [cond-mat.mtrl-sci]

Olivier Isnard, Michael D. Kuz'Min, Manuel Richter, Michael Loewenhaupt, Robert Bewley. A high-energy inelastic neutron scattering investigation of the Gd-Co exchange interactions in GdCo4B: Comparison with density-functional calculations. Journal of Applied Physics, 2008, 104, pp.3922. ⟨10.1063/1.2953099⟩. ⟨hal-00983993⟩