Spin dynamics in highly frustrated pyrochlore magnets

Sylvain Petit (1) , Solène Guitteny (2) , Julien Robert , Pierre Bonville (3, 4) , Claudia Decorse (5) , Jacques Ollivier (6) , Hannu Mutka (6) , Isabelle Mirebeau (2)

1 CRC - Centre de Recherche des Cordeliers
2 LLB - UMR 12 - Laboratoire Léon Brillouin
3 LNO - Laboratoire Nano-Magnétisme et Oxydes
4 SPEC - UMR3680 - Service de physique de l'état condensé
5 ICMMO - Institut de Chimie Moléculaire et des Matériaux d'Orsay
6 ILL - Institut Laue-Langevin

This paper aims at showing the complementarity between time-of-flight and triple-axis neutron scattering experiments, on the basis of two topical examples in the field of geometrical magnetic frustration. Rare earth pyrochlore magnets R 2 Ti 2 O 7 (R is a rare earth) play a prominent role in this field, as they form model systems showing a rich variety of ground states, depending on the balance between dipolar, exchange interactions and crystal field. We first review the case of the XY antiferromagnet Er 2 Ti 2 O 7. Here a transition towards a Néel state is observed, possibly induced by an order-by-disorder mechanism. Effective exchange parameters can be extracted from S(Q, ω). We then examine the case of the spin liquid Tb 2 Ti 2 O 7. Recent experiments reveal a complex ground state characterized by " pinch points " and supporting a low energy excitation. These studies demonstrate the existence of a coupling between crystal field transitions and a transverse acoustic phonon mode.

Domains: Physics [physics]; Environmental Sciences

Sylvain Petit, Solène Guitteny, Julien Robert, Pierre Bonville, Claudia Decorse, et al.. Spin dynamics in highly frustrated pyrochlore magnets. EPJ Web of Conferences, 2015, ⟨10.1051/epjconf/20158303012⟩. ⟨cea-01366317⟩