Yaouanc A, Dalmas de Réotier P, Keller L, Roessli B, Forget A
Université Grenoble Alpes, INAC-PHELIQS, F-38000 Grenoble, France. CEA, INAC-PHELIQS, F-38000 Grenoble, France.
J Phys Condens Matter. 2016 Oct 26;28(42):426002. doi: 10.1088/0953-8984/28/42/426002. Epub 2016 Aug 25.
The pyrochlore insulator Yb2Ti2O7 has attracted the attention of experimentalists and theoreticians alike for about 15 years. Conflicting neutron diffraction data on the possible existence of magnetic Bragg reflections at low temperature have been published. Here we report the observation of magnetic Bragg reflections by neutron powder diffraction at 60 mK. The magnetic diffraction pattern is analyzed using representation theory. We find Yb2Ti2O7 to be a splayed ferromagnet as reported for Yb2Sn2O7, a sibling compound with also dominating ferromagnetic interactions as inferred from the positive Curie-Weiss temperature. However, the configuration of the magnetic moment components perpendicular to the easy axis is of the all-in-all-out type in Yb2Ti2O7 while it is two-in-two-out in the Yb2Sn2O7. An overall experimental picture of the magnetic properties emerges.
