Magnetic fluctuations under pressure on S-doped FeSe studied via 77Se NMR

Takanori Kuwayama,Yoshiya Uwatoko,Yuta Mizukami,Takasada Shibauchi,Shigeru Kasahara,Naoki Fujiwara,Yuji Matsuda,Kohei Matsuura

doi:10.1063/1.5042570

Takanori Kuwayama, Yoshiya Uwatoko + Show 6 more

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https://doi.org/10.1063/1.5042570

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Journal: AIP Advances	Publication Date: Aug 31, 2018
Citations: 1	License type: cc-by

Affiliation: Kyoto University, The University of Tokyo

Abstract

FeSe1-xSx has attracted much attention among iron-based superconductors because the pure sample undergoes nematic and superconducting (SC) phase transitions without magnetism. A pressure-induced antiferromagnetic (AFM) phase emerges upon applying pressure. In the pressure (P)-temperature (T) phase diagram for the 12%-S doped sample, the AFM phase is separated from the nematic phase at around 3.0 GPa, and SC transition temperature (Tc) takes a maximum (∼30 K). We measured T1 of 77Se for the 12%-S doped FeSe at 3.0 GPa. We found from 1/T1T that low-energy AFM fluctuations are not so much enhanced under pressure compared with those at ambient pressure. The result suggests changes of topology and nesting of Fermi surfaces during pressurizing process.

Highlights

The phase diagram determined from the resistivity dramatically changes by sulfur (S) doping: the pressure-induced AFM phase with the dome structure moves to a higher-pressure regime as the doping level is increased.[9]
We investigated the electronic state in a microscopic view point using NMR technique for x = 0.12 where T c marks a high value of 25-30 K without the nematic and AFM orderings
The resonance frequency changes rather sharply at ambient pressure: T c determined from the cross point is 8.6 K and that from the onset is 9.8 K

Summary

Introduction

The phase diagram determined from the resistivity dramatically changes by sulfur (S) doping: the pressure-induced AFM phase with the dome structure moves to a higher-pressure regime as the doping level is increased.[9]. In the x-T phase diagram, the nematic phase is gradually suppressed with increasing the doping level and vanishes at x = 0.17, whereas T c is almost unchanged up to x = 0.17, and slightly changes at x = 0.17. SC, and AFM phases complicatedly overlap each other in the P-T phase diagram for the pure sample, the 12%-S doped sample is preferred to investigate whether a high T c under pressure originates from AFM fluctuations. For this purpose, we investigated the electronic state in a microscopic view point using NMR technique for x = 0.12 where T c marks a high value of 25-30 K without the nematic and AFM orderings

Results

Discussion

Conclusion