Abstract
We performed NMR measurements on an organic superconductor [BETS: bis(ethylenedithio)tetraselenafulvalene] to investigate the pressure effect on the spin density wave (SDW) fluctuations at low temperatures, which were observed at ambient pressure. We found that the spin-lattice relaxation rate divided by temperature is significantly enhanced at low temperatures at 3 kbar, implying enhancement of the SDW fluctuation. When further pressure is applied, increase in at low temperatures is suppressed and becomes temperature independent, indicating the Fermi liquid state. Moreover, we revealed that the Korringa factor under pressure becomes double compared to its value at ambient pressure, suggesting a significant change in electron correlation. We discuss the effect of the SDW fluctuation and the electron correlation on the unconventional superconductivity.
1 More- Received 29 October 2020
- Revised 23 December 2020
- Accepted 23 December 2020
DOI:https://doi.org/10.1103/PhysRevB.103.045112
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