Competing interactions in dysprosium garnets and generalized magnetic phase diagram of S=12 spins on a hyperkagome network

Abstract

The anisotropy and magnetic ground state of hyperkagome dysprosium gallium garnet Dy 3 Ga 5 O 12 are investigated, along with that of its closest structural analog and archetypal Ising multiaxis antiferromagnet, dysprosium aluminum garnet Dy 3 Al 5 O 12 , using a combination of neutron scattering techniques, including polarized neutron powder diffraction. Results show a dramatic change from an Ising-like anisotropy in Dy 3 Al 5 O 12 , to a quasiplanar one in Dy 3 Ga 5 O 12. According to a point charge modeling, this is due to small variations of the oxygen positions surrounding Dy 3+ ions. The magnetic ground state of Dy 3 Ga 5 O 12 is investigated for the first time and is found to be similar to that of Dy 3 Al 5 O 12 , yet with a much lower T N. Mean-field calculations show that the dipolar interaction favors distinct magnetic ground states, depending on the anisotropy tensor: a multiaxis antiferromagnetic state is favored in the case of strong Ising-like anisotropy, like in Dy 3 Al 5 O 12 , whereas a complex ferrimagnetic state is stabilized in the case of planar anisotropy. The Dy 3 Ga 5 O 12 crystal field parameters locate the latter close to the boundary between those two ground states, which, alongside competition between dipolar and a small but finite magnetic exchange, may explain its low T N. To widen the scope of these experimental results, we performed mean-field calculations to generate the magnetic phase diagram of an effective anisotropic pseudospin S = 1/2, characterized by general g xx , g yy , and g zz Landé factors. A very rich magnetic phase diagram, encompassing complex phases, likely disordered, is evidenced when magnetic anisotropy departs from the strong Ising case. With magnetic anisotropy being controllable through appropriate tuning of the rare-earth oxygen environment, these results emphasize the potential of rare-earth hyperkagome networks for the exploration of new magnetic phases.

Identifying, and constructing, complex magnon band topology

“…The moments are oriented along three cubic directions on each triangular face. This structure is observed in the material Dy 3 M 5 O 12 (M=Al,Ga) [79][80][81]. The 24 Wyckoff sites are composed of 12 magnetic sublattices plus a translation through (1/2, /1/2, 1/2) as the lattice is bcc.…”

Magnetocaloric properties of (RE)$_3$Ga$_5$O$_{12}$ (RE=Tb,Gd,Nd,Dy)

“…The three additional samples in this category which were characterized in this work are single crystals of Nd 3 Ga 5 O 12 Neodymium-Gallium-Garnet (NGG) [17,25,26], Tb 3 Ga 5 O 12 Terbium-Gallium-Garnet (TGG) [27][28][29][30][31] and Dy 3 Ga 5 O 12 Dysprosium-Gallium-Garnet (DGG). [6,[32][33][34][35][36][37] The sample shapes are shown in Fig. 2 and listed in Table I.…”

“…1. This structure is geometrically frustrated in three dimensions by virtue of the interwoven hyperkagome lattice motif consisting of a 2D network of corner sharing triangles, facilitating low magnetic ordering temperatures [5,6]. These materials are especially interesting for their non-hysteretic paramagnetic behavior down to sub-liquid-Helium temperatures and their chemical stability, high electric resistance, non-corrosivity, and the possibility for scalable, cost-efficient fabrication.…”

Elucidating Individual Magnetic Contributions in Bi‐Magnetic Fe3O4/Mn3O4 Core/Shell Nanoparticles by Polarized Powder Neutron Diffraction

“…The weak diffraction signal is exacerbated in nanostructured systems since the broadening of the diffraction peaks reduces even further the signalto-background ratio. However, improvements made in neutron instrumentation [32] (focusing monochromators, 3 He spin filters, high field magnets, position sensitive detectors) and the event of a new software, [43] which has already been successfully applied to data treatment of different compounds, [44,45] make PNPD much more attractive.…”