75As-NMR studies on La FeAsO1-xFx (x=0.14) under a pressure of 3GPa

TL;DR

This study uses 75As-NMR to investigate how applying 3GPa pressure enhances the superconducting transition temperature in LaFeAsO1-xFx, revealing increased density of states at the Fermi level as a key factor.

Contribution

First NMR investigation of LaFeAsO1-xFx under high pressure demonstrating the link between density of states and Tc enhancement.

Findings

Tc increases to 40K under 3GPa pressure

Density of states at Fermi level increases with pressure

Anomalous high-temperature behavior is suppressed by pressure

Abstract

75As-nuclear magnetic resonance (NMR) on an iron-based superconductor LaFeAsO1-xFx (x=0.14) was performed under a pressure of 3GPa. Enhancement of superconducting transition temperature Tc was confirmed from the relaxation rate 1/T1; Tc goes up to 40K by applying pressure up to 3GPa. 1/T1T, which is temperature independent just above Tc and gives a measure of the density of states (DOS) at the Fermi energy, enhances by applying pressure. These facts suggest that the increase of the DOS leads to the enhancement of Tc. On the other hand, anomalous behavior of 1/T1T observed at high temperatures is suppressed by applying pressure.