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Séminaire MCBT

Mardi 12 septembre à 11h00,
Salle Louis Weil, E424

"Magnetic fragmentation and quantum effects in Nd2Zr2O7"
Oratrice : Elsa LHOTEL (Institut NEEL)


By means of neutron scattering measurements, we have observed magnetic fragmentation in the pyrochlore oxide Nd2Zr2O7, in which the Nd3+ ion has a strong Ising character and ferromagnetic interactions are inferred from the positive Curie-Weiss temperature θCW = 195 mK [2]. In this system, an “all in - all out” ordered state, with a reduced magnetic moment, coexists below TN = 285 mK with a fluctuating state [3]. Experimentally, the fragmentation manifests itself via the superposition of magnetic Bragg peaks, characteristic of the antiferromagnetic ordered phase, and a pinch point pattern, characteristic of the Coulomb phase [4]. The finite energy of the pinch point pattern and the dispersive modes that emerge from it, points out the quantum origin of the fragmentation in Nd2Zr2O7 [5], which comes from the very peculiar “dipolar-octopolar” nature of the Kramers Nd3+ doublet.

[1] Brooks-Bartlett et al., Phys. Rev. X 4, 011007 (2014).
[2] Ciomaga Hatnean et al. Phys. Rev. B 91, 174416 (2015).
[3] Lhotel et al., Phys. Rev. Lett. 115, 197202 (2015). Xu et al., Phys. Rev. B 92, 224430 (2015).
[4] Petit et al., Nature Phys. 12, 746 (2016).
[5] Benton, Phys. Rev. B 94, 104430 (2016).

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