Phonon and crystal field excitations in geometrically frustrated rare earth titanates

@article{Lummen2008PhononAC,
  title={Phonon and crystal field excitations in geometrically frustrated rare earth titanates},
  author={T T A Lummen and I P Handayani and Michiel C. Donker and Daniele Fausti and Guy Dhalenne and Patrick Berthet and Alexandre Revcolevschi and Paul H.M. van Loosdrecht},
  journal={Physical Review B},
  year={2008},
  volume={77},
  pages={214310}
}
The phonon and crystal field excitations in several rare earth titanate pyrochlores are investigated. Magnetic measurements on single crystals of Gd(2)Ti(2)O(7), Tb(2)Ti(2)O(7), Dy(2)Ti(2)O(7), and Ho(2)Ti(2)O(7) are used for characterization, while Raman spectroscopy and terahertz time domain spectroscopy are employed to probe the excitations in the materials. The lattice excitations are found to be analogous across the compounds over the whole temperature range investigated (295-4 K). The… 

Figures and Tables from this paper

Static magnetic susceptibility, crystal field and exchange interactions in rare earth titanate pyrochlores.
TLDR
Analytical expressions for the site and bulk susceptibilities of the pyrochlore lattice are derived taking into account long range dipole-dipole interactions and anisotropic exchange interactions between the nearest neighbor rare earth ions.
Raman scattering study of delafossite magnetoelectric multiferroic compounds: CuFeO2 and CuCrO2.
  • O. Aktas, K. Truong, +4 authors G. Quirion
  • Chemistry, Physics
    Journal of physics. Condensed matter : an Institute of Physics journal
  • 2012
TLDR
Ultrasonic velocity measurements on the magnetoelectric multiferroic compound CuFeO(2) reveal that the antiferromagnetic transition observed at T(N1) = 14 K might be induced by an R3m --> pseudoproper ferroelastic transition, but analysis of the temperature dependence of the modes in both compounds shows that the frequencies of all modes increase with decreasing temperature.
X-ray diffraction and Raman spectroscopy on Gd2(Ti2−yTey)O7 prepared at high pressure and high temperature
Abstract A series of Te-substituted pyrochlores of stoichiometry Gd 2 (Ti 2− y Te y )O 7 ( y  ≤ 0.2) were prepared under high-pressure and high-temperature conditions and characterized by X-ray
First principles study of zone centre phonons in rare-earth pyrochlore titanates, RE2Ti2O7 (RE = Gd, Dy, Ho, Er, Lu; Y)
Abstract We present first principles study of zone centre phonons in rare-earth pyrochlore titanates, RE 2 Ti 2 O 7 (RE = Gd, Dy, Ho, Er, Lu; Y). The study has been made within the density functional
Magnetic order in hybrid frustrated magnets Gd(2-x)Tb(x)Ti2O7 (x = 0.2 and 0.5).
TLDR
The analysis of experimental data revealed that the frequency-dependent magnetic susceptibility behavior in Gd(1.5)Tb(0.5).5)Ti(2)O(7) is consistent with the formation of a spin-glass-like state indicating a pronounced slowing down of the dynamical response of the studied hybrid magnets.
Crystal-field levels of terbium in pyrochlore compounds R2Ti2O7
Abstract Temperature-dependent infrared spectroscopic study of Tb 3+ f–f transitions has been performed for pyrochlore compounds Tb 2 Ti 2 O 7 , (Y 0.99 Tb 0.01 ) 2 Ti 2 O 7 , and (Gd 0.9 Tb 0.1 ) 2
Lattice dynamics of rare-earth titanates with the structure of pyrochlore R2Ti2O7 (R = Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu): Ab initio calculation
The ab initio calculation has been performed for the crystal structure and the phonon spectrum of titanates with the structure of pyrochlore R2Ti2O7 (R = Gd-Lu). The frequencies and types of
Atomic Displacive Disorder in Bi2Ti2O7
The recently synthesized cubic pyrochlore Bi2Ti2O7 has been shown to possess displacive disorder in both the anion and cation sublattices. Here, the nature and characteristics of the displacive
Structural and Vibrational Properties of Crystals with a Rare-Earth Sublattice: Ab Initio Calculations
We investigated the crystal structure, vibrational and elastic properties of crystals with a rare-earth sublattice related to different structural types at ab initio level of modeling: elpasolite
Does local disorder occur in the pyrochlore zirconates?
TLDR
These studies demonstrate that as the size of the lanthanoid cation decreases, the local structure evolves smoothly from the ideal pyrochlore toward the defect fluorite rather than undergoing an abrupt transformation.
...
1
2
3
4
5
...

References

SHOWING 1-10 OF 73 REFERENCES
Frustrated rare earth magnetism: Spin glasses, spin liquids and spin ices in pyrochlore oxides
Abstract Rare earth-based materials have played a central role in recent efforts to understand the very unconventional behavior of geometrically frustrated magnetic materials. In particular, rare
Bulk magnetization of the heavy rare earth titanate pyrochlores - a series of model frustrated magnets
We describe magnetization measurements on the heavy rare earth titanate pyrochlores R2 Ti2 O7 , where R = Gd, Dy, Ho, Er, Yb, in the temperature range 1.8-300 K, and the field range 0-70 000 Oe. In
Temperature‐dependent Raman scattering studies of the geometrically frustrated pyrochlores Dy2Ti2O7, Gd2Ti2O7 and Er2Ti2O7
The temperature-dependent Raman studies of A2Ti2O7(A = Dy, Er, Gd) were performed on single crystals and polycrystalline samples in the 4.2–295 K temperature range. The Raman spectra showed softening
Structural changes and pressure-induced amorphization in rare earth titanates Re2Ti2O7 (RE: Gd, Sm) with pyrochlore structure
Abstract Structural changes of pyrochlore titanates, Sm 2 Ti 2 O 7 and Gd 2 Ti 2 O 7 , at high pressures were studied by in situ Raman scattering and X-ray diffraction (XRD) methods. The Raman
Spectroscopic Investigations of the Structural Phase Transition in Gd2(Ti1-yZry)2O7 Pyrochlores
The Gd2(Ti1-yZry)2O7 pyrochlore series undergoes a structural phase transition from pyrochlore (Fd3m) to defect fluorite (Fm3m) that can be driven compositionally by increasing the Zr content or
Two geometrically frustrated magnets studied by neutron diffraction
Abstract In the pyrochlore compounds, Tb 2 Ti 2 O 7 and Tb 2 Sn 2 O 7 , only the Tb 3 + ions are magnetic. They exhibit quite abnormal—and, in view of their chemical similarity, strikingly
Multiple field-induced phase transitions in the geometrically frustrated dipolar magnet: Gd(2) Ti(2)O(7).
TLDR
The phase diagram of a frustrated pyrochlore magnet Gd( 2)Ti(2)O(7), where crystal-field splitting is small compared to the dipolar energy, is presented, finding good agreement between zero-temperature critical fields and those obtained from a mean-field model.
Estimation of single ion anisotropy in pyrochlore Dy2Ti2O7, a geometrically frustrated system, using crystal field theory
Abstract From accurate measurement of magnetic susceptibility K of powder sample and single crystal of cubic Dy2Ti2O7 (DyT) between 300 and 70 K, a change of slope of 1/ K was detected at 130 K
Rare‐earth titanates and stannates of pyrochlore structure; vibrational spectra and force fields
Infrared absorption and polarized Raman spectra of rare-earth titanates of pyrochlore structure Ln2Ti2O7 (Ln = Sm, Gd, Yb; Y) and Ln2Sn2O7 (Ln = La, Sm, Gd, Yb, Lu; Y) have been recorded. A valence
The structural transformation from the pyrochlore structure, A2B2O7, to the fluorite structure, AO2, studied by Raman spectroscopy and defect chemistry modeling
Pyrochlore oxides of the composition Y2Ti2−yZryO7, with y= 0, 0.3, 0.6, and 0.9, were studied using Raman spectroscopy. Doping with Zr+4, a homovalent ion, gradually induces the material to undergo a
...
1
2
3
4
5
...