Incommensurate magnetic states induced by ordering competition in $\mathrm{Ba_{1-x}Na_xFe_2As_2}$

TL;DR

This study uses a phenomenological theory and renormalization group approach to explore how magnetic and superconducting fluctuations compete in Ba_{1-x}Na_xFe_2As_2, leading to various incommensurate magnetic states near quantum criticality.

Contribution

It reveals the dominant incommensurate magnetic states and their spin configurations, providing insights into the magnetic phase competition in iron-based superconductors.

Findings

C2-symmetry IC magnetic stripe with perpendicular helix dominates

IC charge spin density wave is favored among C4-symmetry phases

Superfluid density drops sharply with critical temperature dip

Abstract

Quantum criticality nearby a certain magnetic phase transition beneath the superconducting dome of $\mathrm{Ba_{1-x}Na_xFe_2As_2}$ is attentively studied by virtue of a phenomenological theory in conjunction with renormalization group approach. We report that ordering competition between magnetic and superconducting fluctuations is capable of coaxing incommensurate (IC) magnetic states to experience distinct fates depending upon their spin configurations. The $C_2$-symmetry IC magnetic stripe with perpendicular magnetic helix dominates over other $C_2$-symmetry magnetic competitors and hints at a potential candidate for the unknown $C_2$-symmetry magnetic state. Amongst $C_4$-symmetry IC magnetic phases, IC charge spin density wave is substantiated to be superior, shedding light on the significant intertwining of charge and spin degrees of freedom. Meanwhile, ferocious fluctuations render a sharp fall of superfluid density alongside dip of critical temperature as well as intriguing behavior of London penetration depth.