Precise Pressure Dependence of the Superconducting Transition Temperature of FeSe: Resistivity and 77Se-NMR Study

概要

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We report the precise pressure dependence of FeSe from a resistivity measurement up to 4.15 GPa. Superconducting transition temperature ($T_{\text{c}}$) increases sensitively under pressure, but shows a plateau between 0.5–1.5 GPa. The maximum $T_{\text{c}}$, which is determined by zero resistance, is 21 K at approximately 3.5 GPa. The onset value reaches ${\sim}37$ K at 4.15 GPa. We also measure the nuclear spin–lattice relaxation rate $1/T_{1}$ under pressure using 77Se-NMR measurement. $1/T_{1}$ shows that bulk superconductivity is realized in the zero-resistance state. The pressure dependence of $1/T_{1}T$ just above $T_{\text{c}}$ shows a plateau as well as the pressure dependence of $T_{\text{c}}$, which gives clear evidence of the close relationship between $1/T_{1}T$ and $T_{\text{c}}$. Spin fluctuations are suggested to contribute to the mechanism of superconductivity.
Physical Society of Japanの論文
2009-06-15