  Unlike the parent phases of the iron-arsenide high Tc superconductors,
undoped FeSe is not magnetically ordered and exhibits superconductivity with
Tc~9K. Equally surprising is the fact that applied pressure dramatically
enhances the modest Tc to ~37K. We investigate the electronic properties of
FeSe using 77Se NMR to search for the key to the superconducting mechanism. We
demonstrate that the electronic properties of FeSe are very similar to those of
electron-doped FeAs superconductors, and that antiferromagnetic spin
fluctuations are strongly enhanced near Tc. Furthermore, applied pressure
enhances spin fluctuations. Our findings suggest a link between spin
fluctuations and the superconducting mechanism in FeSe.
