Abstract
Measurements of physical properties, including transport and magnetic properties, specific heat, and thermal conductivity, have been performed on high-quality samples of and synthesized under high pressure. Some measurements, such as thermoelectric power and magnetic susceptibility, have been made under high pressure. The availability of a complete set of data enables a side-by-side comparison between these two narrowband systems. We have demonstrated unambiguously the mass enhancement due to electron-electron correlations in both systems relative to the recent density functional theory results. Correlations in these narrowband systems also enhance the magnetic susceptibility. Ferromagnetic spin fluctuations give rise to a strong Stoner enhancement in the magnetic susceptibility in the quarter-filled . Although we are able to tune the bandwidth by either chemical substitutions or by applying hydrostatic pressure on , the Stoner enhancement does not lead to the Stoner instability.
2 More- Received 14 April 2014
- Revised 13 June 2014
DOI:https://doi.org/10.1103/PhysRevB.89.245138
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