Temperature and Magnetic Field Dependence of Spin Ice Correlations in the Pyrochlore Magnet Tb2Ti2O7
| Autor: | Fritsch, K., Kermarrec, E., Ross, K. A., Qiu, Y., Copley, J. R. D., Pomaranski, D., Kycia, J. B., Dabkowska, H. A., Gaulin, B. D. |
|---|---|
| Rok vydání: | 2013 |
| Předmět: | |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1103/PhysRevB.90.014429 |
| Popis: | 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 neutron 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. Comment: 9 pages, 7 figures |
| Databáze: | arXiv |
| Externí odkaz: |
|