Quantalps federation is pleased to announce the following Quantum Materials Seminar by Françoise Damay (LLB).
Abstract: Amongst geometrically frustrated architectures is the hyperkagome lattice, which consists in a twisted spatial arrangement of corner-sharing triangles and which can be found in rare-earth (R) garnets R3B2C3O12 [1]. Mean-field calculations on a hyperkagome lattice, for an effective anisotropic pseudospin S = ½, generate a very rich magnetic phase diagram, encompassing complex disordered phases, when magnetic anisotropy departs from the strong Ising case [2]. Tuning the rare-earth magnetic anisotropy in garnets is the key to exploring this phase diagram, and can be achieved through appropriate distortions of the rare-earth oxygen environment, the latter being controlled by the B and C ionic size. Point charge calculations further underline the potential for interesting magnetocaloric properties for given distortions of the rare-earth cage.
compositions belonging to the R = Dy garnets system have been studied on the basis of extensive neutron diffraction and neutron spectroscopy experiments. Results show that a more distorted oxygen environment favours an Ising anisotropy of the Dy3+ moment [3]. A k = 0 multi axis antiferromagnetic ground state is observed for all compositions, except for a high level of disorder (achieved through high entropy) on the B site, whose lack of ordering still remains to be understood.
[1] S. Geller, Z. Kristallogr. Bd. 125, S1 (1967)
[2] I. Kibalin et al, Phys. Rev. Research 2, 033509, (2020)
[3] F. Damay et al., Phys. Rev. B 109, 014419 (2024)
Published on April 8, 2025
Updated on April 8, 2025
Date
On April 10, 2025
Seminar starts at 2 PM
Location
2nd floor of Building K, Remy Lemaire Hall (K223) CNRS Campus 25 rue des Martyrs 38000 Grenoble
Access to the CNRS campus is restricted. Please bring your badge or contact the organizer (Florence Levy-Bertrand) to gain access to the campus well in advance.
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