Microscopic coexistence of a two-component incommensurate spin density wave with superconductivity in underdoped NaFe$_{0.983}$Co$_{0.017}$As

TL;DR

This study uses NMR measurements to demonstrate microscopic coexistence of superconductivity with a two-component incommensurate spin density wave in underdoped NaFe$_{0.983}$Co$_{0.017}$As, revealing complex magnetic behavior.

Contribution

The paper provides the first microscopic evidence of coexistence of superconductivity with a two-component incommensurate SDW in this compound.

Findings

Incommensurate SDW with two magnetic components identified

Superconductivity coexists microscopically with SDW

Magnetic moments of the SDW components quantified

Abstract

We have performed $^{75}$As and $^{23}$Na nuclear magnetic resonance (NMR) measurements on a single crystal of NaFe$_{0.9835}$Co$_{0.0165}$As and found microscopic coexistence of superconductivity with a two-component spin density wave (SDW). Using $^{23}$Na NMR we measured the spatial distribution of local magnetic fields. The SDW was found to be incommensurate with a major component having magnetic moment ($\sim0.2\,\mu_B$/Fe) and a smaller component with magnetic moment ($\sim0.02\,\mu_B$/Fe). Spin lattice relaxation experiments reveal that this coexistence occurs at a microscopic level.