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Temperature and Magnetic Field Dependence of Spin-Ice Correlations in the Pyrochlore Magnet Tb^2^Ti2O7

Published

Author(s)

K. Fritsch, E. Kermarrec, Kathryn Aileen Ross, Yiming Qiu, John R. Copley, D. Pomaranski, J. B. Kycia, H. A. Dabkowska, B. D. Gaulin

Abstract

We present a parametric study of the diffuse magnetic scattering at (1/2, 1/2, 1/2}) positions in reciprocal space, ascribed to a frozen antiferromagnetic spin ice state in single crystalline Tb2Ti2O7. Our high-resolution neturon scattering measurements show that the elastic (-0.02 meV < E < 0.02 meV) (1/2,1/2,1/2)} scattering develops strongly below 275 mK, and correlates with the opening of a spin gap of 0.06-0.08 meV over most of the Brillouin zone. The concomitant low-lying magnetic spin excitations are weakly dispersive and appear to soften near the (1/2,1/2,1/2}) wave vector at 80 mK. The nature of the transition at 275 mK has many characteristics of spin glass behavior, consistent with ac-susceptibility measurements. The application of a magnetic field of 0.075 T applied along the [1-10] direction destroys the (1/2,1/2,1/2}) elastic scattering, revealing the fragility of this short-range ordered ground state. We construct a refined H-T phase diagram for Tb2Ti2O7 and [1-10] fields which incorporates this frozen spin ice regime and the antiferromagnetic long-range order previously known to be induced in relatively large fields. Specific heat measurements on the same crystal reveal a sharp anomaly at Tc 450 mK and no indication of a transition near 275 mK. We conclude that the higher temperature specific heat peak is not related to the magnetic ordering but is likely a signal of other, nonmagnetic, correlations.
Citation
Physical Review B
Volume
90
Issue
1

Keywords

frustration, spin ice, pyrochlore, spin liquid, magnetism

Citation

Fritsch, K. , Kermarrec, E. , Ross, K. , Qiu, Y. , Copley, J. , Pomaranski, D. , Kycia, J. , Dabkowska, H. and Gaulin, B. (2014), Temperature and Magnetic Field Dependence of Spin-Ice Correlations in the Pyrochlore Magnet Tb^2^Ti<sub>2</sub>O<sub>7</sub>, Physical Review B, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=915187 (Accessed February 26, 2024)
Created July 22, 2014, Updated October 12, 2021