Temperature - pressure phase diagram of the superconducting iron pnictide LiFeP

TL;DR

This study maps the temperature-pressure phase diagram of superconducting LiFeP, revealing a broad superconducting region, absence of spin-density-wave transition, and enhanced magnetic fluctuations, indicating a robust superconducting state linked to its crystal structure.

Contribution

First detailed pressure-dependent phase diagram of LiFeP, showing its superconducting robustness and magnetic fluctuation features compared to LiFeAs.

Findings

Superconductivity persists over a broad temperature-pressure range.

No evidence of spin-density-wave transition in LiFeP.

Magnetic fluctuations are suggested by resistivity behavior.

Abstract

Electrical-resistivity and magnetic-susceptibility measurements under hydrostatic pressure up to p = 2.75 GPa have been performed on superconducting LiFeP. A broad superconducting (SC) region exists in the temperature - pressure (T-p) phase diagram. No indications for a spin-density-wave transition have been found, but an enhanced resistivity coefficient at low pressures hints at the presence of magnetic fluctuations. Our results show that the superconducting state in LiFeP is more robust than in the isostructural and isoelectronic LiFeAs. We suggest that this finding is related to the nearly regular [FeP_4] tetrahedron in LiFeP.