Low-temperature study of an Er2Ti2O7 single crystal synthesized by floating zone technique and simplified feed rod preparation route

Vlášková, K.; Proschek, Petr; Pospíšil, Jiří; Klicpera, M.

doi:10.1016/j.jcrysgro.2020.125783

Cited by 8 publications

(3 citation statements)

References 19 publications

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“…About 3% of unreacted A 2 O 3 oxides was evidenced in the samples of total mass 4.2 and 5.7 g, while the Tm 2 Ir 2 O 7 sample (6.9 g) later used for inelastic neutron scattering experiment contained about 12% of unreacted Tm 2 O 3 . Unreacted initial oxides in the sample are a common problem preparing A 2 Ir 2 O 7 iridates [5,10,13,25,28] due to significantly different melting temperatures of initial oxides and heavy sublimation of iridium dioxide (in contrast with, e.g., isostructural rare-earth titanates [29] or zirconates [36]). The decomposition and evaporation of IrO 2 are mostly suppressed using the flux, in which the oxides are dissolved, allowing a lower reaction temperature [27].…”

Section: Sample Synthesis and Characterizationmentioning

confidence: 99%

Neutron scattering study of the Tm2Ir2O7 pyrochlore iridate

Klicpera

Vlášková²,

Staško³

et al. 2022

Phys. Rev. B

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The newly synthesized Tm 2 Ir 2 O 7 iridate is investigated using neutron scattering techniques. Powder neutron diffraction patterns confirm that Tm 2 Ir 2 O 7 crystallizes in a cubic structure of pyrochlore type, consistent with the rest of the rare-earth A 2 Ir 2 O 7 series, and the crystal structure is preserved down to 0.2 K. The thermal expansion of the crystal lattice is well described by a Debye model of lattice vibrations. A weak magnetic signal consistent with the so-called all-in-all-out magnetic order (AIAO) is traced at low temperature; however, it cannot serve as unambiguous evidence of the AIAO structure in the compound. Nondispersive magnetic excitations in energy-momentum space are observed in inelastic neutron scattering spectra of Tm 2 Ir 2 O 7 . The crystal-field scheme and parameters of the thulium iridate are refined and discussed with respect to the specific heat and magnetization data. The results are supported by mean-field calculations.

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Section: Sample Synthesis and Characterizationmentioning

confidence: 99%

Neutron scattering study of the Tm2Ir2O7 pyrochlore iridate

Klicpera

Vlášková²,

Staško³

et al. 2022

Phys. Rev. B

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“…The A 2 Zr 2 O 7 samples with A = Y, La, Nd, Eu, Gd, Tb, Dy, Ho, Tm, Yb, and Lu were synthesised using a preparation recipe described in detail in our recent publications [15,[39][40][41]. The initial mixture of A 2 O 3 and ZrO 2 oxides (purity of 99.99% metal basis, AlfaAesar) was prepared in the 1:2 stoichiometric molar ratio and thoroughly homogenised by grinding.…”

Section: Sample Synthesis Characterisation and Experimental Detailsmentioning

confidence: 99%

Low-temperature properties of magnetically frustrated rare-earth zirconates A ₂Zr₂O₇

Vojtasová,

Staško,

Hájek

et al. 2024

J. Phys.: Condens. Matter

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Rare-earth A 2Zr2O7 zirconates have attracted considerable attention of the scientific community for their complex magnetic, electronic and material properties applicable in modern technologies. Light rare-earth members of the series, crystallising in the so-called pyrochlore variant of cubic crystal structure, have been studied in detail. HeavierA 2Zr2O7 compounds have been investigated mainly from the material properties viewpoint, focussing on their thermal properties and stability at high temperature and pressure. Low-temperature studies were mostly missing until recently. We present the low-temperature magnetic and thermodynamic properties of A 2Zr2O7 with A = Y, La, Nd, Eu, Gd, Tb, Dy, Ho, Tm, Yb, and Lu, well covering the whole series,the heavy rare-earth zirconates newly synthesised by high-temperature sintering and melting methods. X-ray diffraction reveals/confirms the ordered pyrochlore structure in light members, the disordered cubic structure of the defect-fluorite type in A 2Zr2O7 with A = Y, Gd – Yb, and the lower symmetry rhombohedral structure in the end-member Lu2Zr2O7. The specific heat of investigated compounds is dominated by the low-temperature anomaly associated with the magnetic ordering, long-range in light rare-earth zirconates, and short-range in heavier members. Effective magnetic moment in studied compounds, determined by fitting the magnetisation data to the Curie-Weiss formula, is in good agreement with the value of the A 3+ free ion. The magnetic properties were documented to be strongly influenced by the frustration of magnetic moments, connected to atomic disorder on the geometrically frustrated lattice. The experimental results are discussed in the framework of previous studies on A 2Zr2O7 zirconates, as well as other A 2 B 2O7 compounds.

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“…To complement and confirm the theories, model materials must be found and studied, as close as possible to the ideal case. Pyrochlore lattices of magnetic ions exist in a number of real materials, most commonly in both the spinel, AB 2 O 4 , and pyrochlore, A 2 B 2 O 7 , oxides [7][8][9][10][11]. Structural stability and charge balancing constraints of the pyrochlore oxides mean that the magnetic ions that are most commonly hosted are rare-earth A 3+ ions.…”

Section: Introductionmentioning

confidence: 99%

Structural and spin-glass properties of single crystal J _eff = ½ pyrochlore antiferromagnet NaCdCo₂F₇: correlating T _f with magnetic-bond-disorder

2023

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Weak bond disorder disrupts the expected spin-liquid ground-state of the ideal S = 1/2 Heisenberg pyrochlore antiferromagnet. Here we introduce a single crystal study of the structural and magnetic properties of the bond-disordered pyrochlore NaCdCo2F7. The magnetic susceptibility appears isotropic, with a large negative Curie-Weiss temperature (θCW = -108(1) K), however no magnetic order is observed on cooling until a spin-glass transition at Tf = 4.0 K. AC-susceptibility measurements show a frequency-dependent shift of the associated cusp in χ’ at Tf, that can be fitted well by the empirical Vogel-Fulcher law. The magnetic moment of µeff = 5.4(1) µB/Co2+ indicates a significant orbital contribution and heat capacity measurements show that down to 1.8 K, well below Tf, only Smag ~2⁄3 Rln(2) of the magnetic entropy is recovered, suggestive of residual continued dynamics. Structural and magnetism comparisons are made with the other known members of the NaA’’Co2F7 family (A’’ = Ca2+, Sr2+), confirming the expected relationship between spin-glass freezing temperature, and extent of magnetic bond disorder brought about by the size mismatch between A-site ions.

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Low-temperature study of an Er2Ti2O7 single crystal synthesized by floating zone technique and simplified feed rod preparation route

Cited by 8 publications

References 19 publications

Neutron scattering study of the Tm2Ir2O7 pyrochlore iridate

Neutron scattering study of the Tm2Ir2O7 pyrochlore iridate

Low-temperature properties of magnetically frustrated rare-earth zirconates A ₂Zr₂O₇

Structural and spin-glass properties of single crystal J _eff = ½ pyrochlore antiferromagnet NaCdCo₂F₇: correlating T _f with magnetic-bond-disorder

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Low-temperature study of an Er2Ti2O7 single crystal synthesized by floating zone technique and simplified feed rod preparation route

Cited by 8 publications

References 19 publications

Neutron scattering study of the Tm2Ir2O7 pyrochlore iridate

Neutron scattering study of the Tm2Ir2O7 pyrochlore iridate

Low-temperature properties of magnetically frustrated rare-earth zirconates A 2Zr2O7

Structural and spin-glass properties of single crystal J eff = ½ pyrochlore antiferromagnet NaCdCo2F7: correlating T f with magnetic-bond-disorder

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Low-temperature properties of magnetically frustrated rare-earth zirconates A ₂Zr₂O₇

Structural and spin-glass properties of single crystal J _eff = ½ pyrochlore antiferromagnet NaCdCo₂F₇: correlating T _f with magnetic-bond-disorder