# $^{77}$Se-NMR Study under Pressure on 12%-S Doped FeSe

## TL;DR

This study uses $^{77}$Se-NMR under pressure to explore the microscopic properties of 12%-S doped FeSe, revealing suppressed AFM fluctuations at optimal pressure and a double-dome superconducting phase structure under high magnetic field.

## Contribution

First microscopic investigation of 12%-S doped FeSe under pressure using $^{77}$Se-NMR, uncovering suppressed AFM fluctuations and a double-dome superconducting phase.

## Key findings

- Suppressed AFM fluctuations at optimal pressure (~3 GPa).
- Double-dome superconducting phase observed under high magnetic field.
- High Tc of 30 K achieved at 3.0 GPa.

## Abstract

The 12%-S doped FeSe system has a high Tc of 30 K at a pressure of 3.0 GPa. We have successfully investigated its microscopic properties for the first time via $^{77}$Se-NMR measurements under pressure. The antiferromagnetic (AFM) fluctuations at the optimal pressure (~3 GPa) exhibited unexpected suppression compared with the AFM fluctuations at ambient pressure, even though the optimal pressure is close to the phase boundary of the AFM phase induced at the high-pressure region. In addition, we revealed that the SC phase at an applied field of 6.02 T exhibited a remarkable double-dome structure in the pressure-temperature phase diagram, unlike the SC phase at zero field.