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Séminaire MCBT : mardi 6 décembre 2022 à 11h00

Quentin Faure

Titre : Low-energy spin dynamics in the diluted pyrochlore iridate Tb(2+x)Ir(2-x)O(7-y) (x = 0.4) probed by Resonant Inelastic X-rays Scattering


Institut Néel, Salle E424
Résumé : The present talk is devoted to the study of the low-energy spin-dynamics of the diluted (non-stoichiometric) compound Tb(2+x)Ir(2-x)O7-y (x = 0.3). Besides the fact that the spin-dynamics of only few members of the pyrochlore iridates’ family have been investigated, the motivation of this study lies into two points. First, recent resistivity measurements which showed that magnetic dilution lowers the electronic correlations hence leading to compounds more metallic. Second, the spin-dynamics response from a magnetic system is closely linked to either its itinerant or localized character. Hence the study of the spin dynamics, in addition to probe the microscopic parameters of the low-energy Hamiltonian, could be considered as an indirect way to elucidate the strength of the electronic correlations in pyrochlore iridates. After briefly exposing magnetometry and resistivity measurements to characterize this compound, I will expose recent Resonant Inelastic X-rays Scattering (RIXS) measurements that allowed us to probe the spin-dynamics of this compound along high-symmetry directions of the Brillouin zone. In addition, we performed spin-waves calculations using spinW software that allowed us to extract the microscopic parameters of the low-energy Hamiltonian. Finally, I will discuss about discrepancies between experimental results and a strong correlations approach assumed in spin-waves calculations that could be indicative of weaker correlations in this compound