Structural properties of the geometrically frustrated pyrochlore Tb2Ti2O7

Abstract

Although materials that exhibit nearest-neighbor-only antiferromagnetic interactions and geometrical frustration theoretically should not magnetically order in the absence of disorder, few such systems have been observed experimentally. One such system appears to be the pyrochlore Tb2Ti2O7. However, previous structural studies indicated that Tb2Ti2O7 is an imperfect pyrochlore. To clarify the situation, we performed neutron powder diffraction (NPD) and x-ray absorption fine structure (XAFS) measurements on samples that were prepared identically to those that show no magnetic order. The NPD measurements show that the long-range structure of Tb2Ti2O7 is well ordered with no structural transitions between 4.5 and 600 K. In articular, mean-squared displacements (u^2's) for each site follow a Debye model with no offsets. No evidence for Tb/Ti site interchange was observed within an upper limit of 2%. Likewise, no excess or deficiency in the oxygen stoichiometry was observed, within an upper limit of 2% of the nominal pyrochlore value. Tb L3- and Ti K-edge XAFS measurements from 20-300 K similarly indicate a well-ordered local structure. Other aspects of the structure are considered. We conclude that Tb2Ti2O7 has, within experimental error, an ideal, disorder-free pyrochlore lattice, thereby allowing the system to remain in a dynamic, frustrated spin state to the lowest observed temperatures.

7 pages, 5 figures

References in corpus (1)

• Frustration driven lattice distortion; an NMR investigation of Y2Mo2O7

Cited by in corpus (19)

• Magnetic Pyrochlore Oxides
• Lightly stuffed pyrochlore structure of single-crystalline Yb2Ti2O7 grown by the optical floating zone technique
• Phonon and crystal field excitations in geometrically frustrated rare earth titanates
• Structural Fluctuations in the Spin Liquid State of Tb2Ti2O7
• 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 $L{u}_{2}T{i}_2{O}_7$
• Coulomb spin liquid in anion-disordered pyrochlore Tb${}_2$Hf${}_2$O${}_7$
• Spin-Ice State of the Quantum Heisenberg Antiferromagnet on the Pyrochlore Lattice
• Quantum spin fluctuations in the spin liquid state of Tb2Ti2O7
• Crystal field states of Tb3+ in the pyrochlore spin liquid Tb2Ti2O7 from neutron spectroscopy
• The Valence Bond Glass phase
• 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
• Field induced spin ice like orders in spin liquid Tb${}_2$Ti${}_2$O${}_7$
• Sample independence of magnetoelastic excitations in the rare earth pyrochlore Tb2Ti2O7
• Crystal growth and characterization of the pyrochlore Tb${}_2$Ti${}_2$O${}_7$
• Concurrence of ferroelectric, dielectric and magnetic behaviour in Tb2Ti2O7 pyrochlore
• Absence of anomalous negative lattice-expansion for polycrystalline sample of Tb2Ti2O7
• Spin-lattice Coupling in U(1) Quantum Spin Liquids