P-T phase diagram of iron arsenide superconductor NdFeAsO0.88F0.12

TL;DR

This study investigates how high pressure affects the superconducting transition temperature and transport properties of NdFeAsO0.88F0.12, revealing a linear decrease in TC and the disappearance of superconductivity above 18.4 GPa, with a proposed phase diagram.

Contribution

It provides the first detailed pressure-dependent transport study of NdFeAsO0.88F0.12 and proposes a P-T phase diagram for this iron-based superconductor.

Findings

TC decreases linearly with pressure at -2.8 K/GPa

Superconductivity vanishes above ~18.4 GPa

Resistance shows a slope change and possible Kondo effect or localization

Abstract

NdFeAsO0.88F0.12 belongs to the recently discovered family of high-TC iron-based superconductors. The influence of high pressure on transport properties of this material has been studied. Contrary to La-based compounds, we did not observe a maximum in TC under pressure. Under compression, TC drops rapidly as a linear function of pressure with the slope k = -2.8 \pm 0.1 K / GPa. The extrapolated value of TC at zero pressure is about TC (0) = 51.7 \pm 0.4 K. At pressures higher than ~18.4 GPa, the superconducting state disappears at all measured temperatures. The resistance changes slope and shows a turn-up behavior, which may be related to the Kondo effect or a weak localization of two-dimensional carriers below ~45 K that is above TC and thus competing with the superconducting phase. The behavior of the sample is completely reversible at the decompression. On the bases of our experimental data, we propose a tentative P-T phase diagram of NdFeAsO0.88F0.12.