Abstract
We examine the resistivity and thermopower of single crystal specimens of the pyrochlore oxide at pressures up to 2 GPa. Thermopower proves to be a sensitive tool in the study of the phase diagram of The 200 K metal-to-metal phase transition is accompanied by a strong increase of the absolute value of the thermopower. A weaker anomaly allows us to identify a second phase transition at 125 K. Following the temperature dependence of this anomaly, we obtain the corresponding phase boundary up to 1.2 GPa, and argue that it must drop to before p reaches 1.8 GPa. There is a wide temperature range where the electrical properties are fairly sensitive to pressure, indicating the strong coupling of the electronic degrees of freedom to the lattice.
- Received 9 December 2002
DOI:https://doi.org/10.1103/PhysRevB.67.245112
©2003 American Physical Society