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MA: Fachverband Magnetismus

MA 19: Magnetic Materials III

MA 19.7: Vortrag

Dienstag, 8. März 2016, 13:00–13:15, H31

Study of the geometrically frustrated compound Nd₂Sn₂O₇ — •Bertin A.¹, Dalmas de Réotier P.^2,3, Fåk B.⁴, Marin C.^2,3, Yaouanc A.^2,3, Forget A.⁵, Sheptyakov D.⁶, Frick B.⁴, Ritter C.⁴, Amato A.⁷, Baines C.⁷, and King P.J.C.⁸ — ¹TU Dresden — ²Univ. Grenoble Alpes — ³CEA-Grenoble, INAC-SPSMS — ⁴Institut Laue-Langevin — ⁵CEA-Saclay, Iramis, SPEC — ⁶Paul Scherrer Institute, SINQ — ⁷Paul Scherrer Institute, SµS — ⁸ISIS Facility, Rutherford Appleton Laboratory

We have undertaken the study of the antiferromagnet pyrochlore compound Nd₂Sn₂O₇ where frustration lattice consists of magnetic ions sitting on a corner-shared tetrahedra network. This compound undergoes a second-order phase transition at T_c=0.91 K into a non collinear "all-in-all-out" magnetic structure, confirmed by the presence of spontaneous oscillations resolved with zero-field µSR measurements. Persistent spin dynamics has been revealed through the temperature independent behaviour of the spin-lattice relaxation rate at low temperatures, and ascribed to 1-dimensional spin-loop excitations. This feature, together with the spin-wave-like excitations seen by specific heat measurements at low temperatures, are barely compatible with a purely Ising spin system and point to the existence of transverse exchange terms. Hence, the anisotropic Hamiltonian for dipolar-octupolar doublet will be discussed. Anomalously long paramagnetic fluctuations have also been revealed by µSR and neutron backscattering experiments up to ≈ 30 T_c. The funding of the current position of the presenting author by BMBF project 05K13ODA is acknowledged.