Phonon and crystal field excitations in geometrically frustrated rare earth titanates

Abstract

The phonon and crystal field excitations in several rare earth titanate pyrochlores are investigated. Magnetic measurements on single crystals of Gd2Ti2O7, Tb2Ti2O7, Dy2Ti2O7 and Ho2Ti2O7 are used for characterization, while Raman spectroscopy and terahertz time domain spectroscopy are employed to probe the excitations of the materials. The lattice excitations are found to be analogous across the compounds over the whole temperature range investigated (295-4 K). The resulting full phononic characterization of the R2Ti2O7 pyrochlore structure is then used to identify crystal field excitations observed in the materials. Several crystal field excitations have been observed in Tb2Ti2O7 in Raman spectroscopy for the first time, among which all of the previously reported excitations. The presence of additional crystal field excitations, however, suggests the presence of two inequivalent Tb3+ sites in the low temperature structure. Furthermore, the crystal field level at approximately 13 cm-1 is found to be both Raman and dipole active, indicating broken inversion symmetry in the system and thus undermining its current symmetry interpretation. In addition, evidence is found for a significant crystal field-phonon coupling in Tb2Ti2O7. These findings call for a careful reassessment of the low temperature structure of Tb2Ti2O7, which may serve to improve its theoretical understanding.

arXiv comment13 pages, 7 figures

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Cited by in corpus (31)

• Structural distortion and the spin liquid state in Tb2Ti2O7
• Raman scattering study of delafossite magnetoelectric multiferroic compounds: CuFeO2 and CuCrO2
• Long-range order and spin-liquid states of polycrystalline Tb${}_{2+x}$Ti${}_{2-x}$O${}_{7+y}$
• Temperature dependent Raman and x-ray studies of spin-ice pyrochlore $D{y}_{2}T{i}_2{O}_7$ and non-magnetic pyrochlore $L{u}_{2}T{i}_2{O}_7$
• Crystal field parameters of the rare earth pyrochlores $R_2$Ti${}_2$O${}_7$ ($R$ = Tb, Dy, Ho)
• Dynamics of Topological Excitations in a Model Quantum Spin Ice
• Synthesis, floating zone crystal growth and characterization of the Quantum Spin Ice $\mathrm{P}{\mathrm{r}}_2\mathrm{Z}{\mathrm{r}}_2{\mathrm{O}}_7$ pyrochlore
• Spin liquid correlations, anisotropic exchange and symmetry breaking in Tb2Ti2O7
• Magnetically originated phonon-glass-like behavior in Tb_2Ti_2O_7 single crystal
• Experimental signatures of quantum and topological states in frustrated magnetism
• Magnetoelastics of a spin liquid: X-ray diffraction studies of Tb2Ti2O7 in pulsed magnetic fields
• Low-temperature magnetization in geometrically frustrated Tb2Ti2O7
• Crystal field states of Tb3+ in the pyrochlore spin liquid Tb2Ti2O7 from neutron spectroscopy
• First principles calculation and experimental investigation of lattice dynamics in the rare earth pyrochlores R2Ti2O7 (R=Tb, Dy, Ho)
• Low temperature and high pressure Raman and x-ray studies of pyrochlore Tb${}_2$Ti${}_2$O${}_7$ : phonon anomalies and possible phase transition
• Multiferroic CuCrO2 under High Pressure: In-Situ X-Ray Diffraction and Raman Spectroscopic Studies
• Double Vibronic process in the quantum spin ice candidate Tb${}_2$Ti${}_2$O${}_7$ revealed by terahertz spectroscopy
• Sample independence of magnetoelastic excitations in the rare earth pyrochlore Tb2Ti2O7
• Investigations of the effect of nonmagnetic Ca substitution for magnetic Dy on spin-freezing in Dy2Ti2O7
• Simulations of magnetic and magnetoelastic properties of Tb2Ti2O7 in paramagnetic phase
• Curie-law crossover in spin liquids
• Crystal Field and Magnetoelastic Interactions in Tb2Ti2O7
• Common Glass-Forming Spin-Liquid State in the Pyrochlore Magnets Dy${}_2$Ti${}_2$O${}_7$ and Ho${}_2$Ti${}_2$O${}_7$
• Exchange renormalized crystal field excitation in a quantum Ising magnet KTmSe${}_2$
• Experimental identification of electric dipoles induced by magnetic monopoles in Tb2Ti2O7
• Emergent order in the spin-frustrated system DyxTb2-xTi2O7 studied by ac susceptibility measurements
• Terahertz Magneto-optical investigation of quadrupolar spin-lattice effects in magnetically frustrated Tb2Ti2O7
• Low Energy Magneto-optics of Tb${}_2$Ti${}_2$O${}_7$ in [111] Magnetic Field
• Crystalline electric field excitations and their nonlinear splitting under magnetic fields in YbOCl
• Effective spin-1/2 exchange interactions in Tb${}_2$Ti${}_2$O${}_7$
• Magnetic field tuning of crystal field levels and vibronic states in Spin-ice Ho${}_2$Ti${}_2$O${}_7$ observed in far-infrared reflectometry