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Emergent magnetic phases induced by a staggered field in pyrochlore iridates - Elsa Lhotel

Institut Néel, Grenoble


LPS – S208a

Pyrochlore oxides, in which magnetic ions lie at the vertices of two interpenetrated lattices of corner-sharing tetrahedra, form a rich playground to explore novel magnetic states induced by frustration. In the specific case of pyrochlore iridates R2Ir2O7 (R = rare-earth), the iridium ion orders at about 100 K thus far above the energy range of the interactions between rare-earth ions (which are about a few Kelvins), thus creating a molecular magnetic field on the rare-earth sublattice. In this talk, I will show that new phases can be stabilized due to the competition between this molecular field and the magnetic interactions or anisotropy of the rare-earth.

I will present two examples. i) The case of antiferromagnetic interactions and Heisenberg spins, with the Gd iridate, in which we observe the decoupling of the magnetic components in two non- collinear antiferromagnetic orderings [1]. ii) The case of ferromagnetic interactions and Ising spins, with the Dy and Ho iridates, in which we have shown the existence of magnetic fragmentation, leading to the superposition of a magnetically antiferromagnetic ordered phase and a persistently fluctuating one with ferromagnetic correlations [2].

[1] E. Lefrançois et al., Phys. Rev. B 99, 060401(R) (2019).

[2] E. Lefrançois et al., Nature Commun. 8, 209 (2017).

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