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Univ. Paris-Saclay
Ground state selection in dipole-octupole Ce-based pyrochlores
Bruce D. Gaulin
Mc Master University, Canada, Ontario
Mercredi 28/06/2023, 11:00
LLB - Bât 563 p15 (Grande Salle), CEA-Saclay

Pyrochlore magnets have been a playground for exotic magnetic ground states as many of these are characterized by quantum S=1/2 degrees of freedom decorating a three dimensional network of corner-sharing tetrahedra - one of the canonical crystalline architectures supporting geometrical frustration in materials.  Recently, we and others have been studying Ce-based pyrochlores, including Ce2Zr2O7 and Ce2Sn2O7, whose S=1/2 degrees of freedom possess both a dipolar and an octupolar character, by virtue of the symmetry properties of Ce3+'s ground state crystal field doublet.  In principle, this allows a ground state phase diagram for such materials that includes both ordered and quantum disordered ground states each of which can have either dipolar character or octupolar character. I will discuss how this exotic dipole-octupole S=1/2 degree of freedom arises in the J=5/2 Ce3+ ion in this environment. I will then review our recent experimental work, based mainly of low temperature thermodynamics and neutron scattering, that makes the case that Ce2Zr2O7 displays a disordered quantum spin ice ground state, while Ce2Sn2O7 is a candidate for an ordered All In - All Out Neel state.

Contact : Sylvain PETIT


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