Résumé

As a conclusion, one can say that the main goal of this report was reached: spin wave dispersion was calculated for Nd2Fe14B crystal samples which were also prepared for neutron scattering experiment. Indeed, several steps were made in order to perform such experiment. First, one needs to select a couple of samples and analyse them with X-ray (Laue method) to know the orientation of their reciprocal axis. Then, after checking their quality and their homogeneity, one can place them on a holder and start the neutron experiment. This was successful in our case where 5 samples out of 6 were judged acceptable for the experiment. Computing spin wave dispersion, we found out that the main interactions in Nd2Fe14B were between iron atoms and especially in the (a,b)-plane. However, this study of spin wave was restricted to a phase where all spins were pointing along the c-axis; nothing was done for the canted phase below TS = 135:94 K which could have been interesting but more difficult to obtain.

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