Magnetic properties and crystal field in MgYb2S4 and MgYb2Se4 spinels

Pawlak, L.; Duczmal, Marek; Zygmunt, A.

doi:10.1016/0304-8853(88)90367-8

Cited by 10 publications

(10 citation statements)

References 3 publications

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“…Unfortunately, there does not appear to have been direct measurements of the crystal field spectrum, and thus the composition of the ground doublet, for any of the ytterbium spinels. While several estimates [27,43,44,74] exist in the literature, they are based on fitting of the magnetic susceptibility and use restricted, mostly cubic, ansatzes for the crystal field interaction parameters. These thus produce nearly perfect Γ 6 ground state doublets and thus essentially reproduce the results of Sec.…”

Section: A Spinelsmentioning

confidence: 99%

Frustration and anisotropic exchange in ytterbium magnets with edge-shared octahedra

2018

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We consider the structure of anisotropic exchange interactions in ytterbium-based insulating rare-earth magnets built from edge-sharing octahedra. We argue the features of trivalent ytterbium and this structural configuration allow for a qualitative determination of the different anisotropic exchange regimes that may manifest in such compounds. The validity of such super-exchange calculations is tested through comparison to the wellcharacterized breathing pyrochlore compound Ba 3 Yb 2 Zn 5 O 11 . With this in hand, we then consider applications to three-dimensional pyrochlore spinels as well as two-dimensional honeycomb and triangular lattice systems built from such edge-sharing octahedra. We find an extended regime of robust emergent weak anisotropy with dominant antiferromagnetic Heisenberg interactions as well as smaller regions with strong anisotropy. We discuss the implications of our results for known compounds with the above structures, such as the spinels AYb 2 X 4 (A = Cd, Mg, X = S, Se), the triangular compound YbMgGaO 4 , which have recently emerged as promising candidates for observing unconventional magnetic phenomena. Finally, we speculate on implications for the R 2 M 2 O 7 pyrochlore compounds and some little studied honeycomb ytterbium magnets.

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Section: A Spinelsmentioning

confidence: 99%

Frustration and anisotropic exchange in ytterbium magnets with edge-shared octahedra

2018

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“…For MgYb 2 Se 4 , we find g = 5.188(79) and g ⊥ = 0.923(85) µ B , implying an effective spin with strong anisotropy along the 111 direction while falling far short of the Ising limit. These values imply significantly more anisotropy than the values of g = 3.564 and g ⊥ = 2.204 obtained from rescaling the CEF parameters from our previous MgEr 2 Se 4 results [31,55], and are even farther removed from reports of nearly isotropic spins determined from fits of inverse magnetic susceptibility curves [40,50]. Comparing the CEF parameters from these and the current study, the starkest contrast lay in the signs of B 43 and B 63 parameters and the magnitude of B 20 .…”

Section: Results and Interpretationmentioning

confidence: 53%

“…For MgYb 2 Se 4 , the parameters B 6m |m = 0, 3, 6 have little consequence on the relative sizes of g and g ⊥ , and on the goodness of the fit to our data, however both B 20 and the ratio between B 40 and B 43 are strongly associated with trigonal fields and thus the tendency of moments to point in the 111 directions. The magnetic susceptibility studies [40,50] underestimate the B 20 parameter and, more consequentially, fix the ratio between B 40 and B 43 to that expected in a perfect octahedral en- vironment. This hugely underestimates the contribution to the potential from the next nearest neighbor atoms, and is likely responsible for the resultant underestimation of the anisotropy of the Yb 3+ ions.…”

Section: Results and Interpretationmentioning

confidence: 90%

“…There thus exists a strong motivation for systematic and high precision measurements of the CEF Hamiltonian across this family of compounds. Some early studies of cadmium spinels acquired this information through careful fits of magnetization data, however the stated results are broadly inconsistent with conclusions from modern studies [36][37][38][39][40]. In the current paper, we instead measure crystal field excitations directly using inelastic neutron scattering (INS), and use fits of both the energy and intensity of observed modes to determine the most likely CEF Hamiltonian consistent with the symmetry of the F d3m space group.…”

Section: Introductionmentioning

confidence: 85%

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Neutron scattering measurement of crystalline-electric fields in magnesium rare-earth selenide spinels

Reig-i-Plessis

Cote

Geldern

et al. 2019

Phys. Rev. Materials

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The symmetry of local moments plays a defining role in the nature of exotic grounds states stabilized in frustrated magnetic materials. We present inelastic neutron scattering (INS) measurements of the crystal electric field (CEF) excitations in the family of compounds MgRE2Se4 (RE ∈ {Ho, Tm, Er and Yb}). These compounds form in the spinel structure, with the rare earth ions comprising a highly frustrated pyrochlore sublattice. Within the symmetry constraints of this lattice, we fit both the energies and intensities of observed modes in the INS spectra to determine the most likely CEF Hamiltonian for each material and comment on the ground state wavefunctions in the local electron picture. In this way, we experimentally confirm MgTm2Se4 has a non-magnetic ground state, and MgYb2Se4 has effective S = 1 2 spins with g = 5.188(79) and g ⊥ = 0.923(85) µB. The spectrum of MgHo2Se4 indicates a ground state doublet containing Ising spins with g = 2.72(46), though low-lying CEF levels are also seen at thermally accessible energies δE = 0.591(36), 0.945(30) and 2.88(7) meV, which can complicate interpretation. These results are used to comment on measured magnetization data of all compounds, and are compared to published results on the material MgEr2Se4. :1906.10767v1 [cond-mat.dis-nn] arXiv

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“…4.. The crystal field states of the chalcogenide spinels were first studied in the 1970's [43][44][45][46][47]. The accuracy of these studies was limited by their assumption of a perfect octahedral environment and also because magnetization data alone was used for the refinements of the CEF Hamiltonian.…”

Section: Rare Earth Chalcogenide Spinelsmentioning

confidence: 99%

Frustrated Magnetism in Fluoride and Chalcogenide Pyrochlore Lattice Materials

Reig-i-Plessis,

Hallas

2020

Preprint

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Pyrochlore lattices, which are found in two important classes of materials -the A2B2X7 pyrochlore family and the AB2X4 spinel family -are the quintessential 3-dimensional frustrated lattice architecture. While historically oxides (X = O) have played the starring role in this field, the past decade has seen material's synthesis breakthroughs that have lead to the emergence of fluoride (X = F) and chalcogenide (X = S, Se) pyrochlore lattice materials. In this Research Update, we summarize recent progress in understanding the magnetically frustrated ground states in three families of non-oxide pyrochlore lattice materials: (i) 3d-transition metal fluoride pyrochlores, (ii) rare earth chalcogenide spinels, and (iii) chromium chalcogenide spinels with a breathing pyrochlore lattice. We highlight how the change of anion may modify the single ion spin anisotropy due to crystal electric field effects, stabilize new magnetic atom combinations, or dramatically alter the exchange pathways and thereby lead to new magnetic ground states. We also consider a slate of future directions -materials with the potential to define the next decade of research in frustrated magnetism.

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Magnetic properties and crystal field in MgYb2S4 and MgYb2Se4 spinels

Cited by 10 publications

References 3 publications

Frustration and anisotropic exchange in ytterbium magnets with edge-shared octahedra

Frustration and anisotropic exchange in ytterbium magnets with edge-shared octahedra

Neutron scattering measurement of crystalline-electric fields in magnesium rare-earth selenide spinels

Frustrated Magnetism in Fluoride and Chalcogenide Pyrochlore Lattice Materials

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