Regensburg 2019 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 6: Frustrated Magnets - Spin Liquids (joint session TT/MA)

MA 6.8: Vortrag

Montag, 1. April 2019, 17:00–17:15, Theater

Intermultiplet transitions and long-range order in Sm-based pyrochlores — •Viviane Peçanha-Antonio¹, Erxi Feng¹, Devashibhai Adroja², Fabio Orlandi², Xiao Sun³, Yixi Su¹, and Thomas Brückel³ — ¹Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ), Forschungszentrum Jülich GmbH, Garching, Germany — ²ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, United Kingdom — ³Jülich Centre for Neutron Science (JCNS) and Peter Grünberg Institut (PGI), Forschungszentrum Jülich GmbH, Jülich, Germany

We present bulk and neutron scattering measurements performed on the isotopically enriched ¹⁵⁴Sm₂Ti₂O₇ and ¹⁵⁴Sm₂Sn₂O₇ samples. Both compounds display sharp heat capacity anomalies, at 350 mK and 440 mK, respectively. Inelastic neutron scattering measurements are employed to solve the crystalline electric field (CEF) excitations scheme, which includes transitions between the ground and first excited J multiplets of the Sm³⁺ ion. To further validate those results, the single-ion magnetic susceptibility of the compounds is calculated and compared with the experimental dc-susceptibility measured in low applied magnetic fields. It is demonstrated that the inclusion of intermultiplet transitions in the CEF analysis is fundamental to the understanding of the intermediate and, more importantly, low temperature magnetic behaviour of the Sm-based pyrochlores. Finally, the heat capacity anomaly is shown to correspond to the onset of an all-in-all-out long-range order in the stannate sample, while in the titanate a dipolar long-range order can be only indirectly inferred.