The influence of the structural transition on magnetic fluctuations in NaFeAs

TL;DR

This study investigates how the structural transition in NaFeAs influences magnetic fluctuations, revealing a plateau in spin response linked to orbital ordering and anisotropic spin dynamics that may explain nematic phase properties.

Contribution

It provides new insights into the impact of structural transitions on spin dynamics and orbital ordering in Fe-based superconductors, highlighting the role of anisotropic magnetic fluctuations.

Findings

Observation of a plateau in dynamic spin response near T_S.

Identification of spin fluctuation stiffening due to orbital ordering.

Detection of anisotropic spin dynamics above T_S at T*.

Abstract

NaFeAs belongs to a class of Fe-based superconductors which parent compounds show separated structural and magnetic transitions. Effects of the structural transition on spin dynamics therefore can be investigated separately from the magnetic transition. A plateau in dynamic spin response is observed in a critical region around the structural transition temperature T_S. It is interpreted as due to the stiffening of spin fluctuations along the in-plane magnetic hard axis due to the dxz and dyz orbital ordering. The appearance of anisotropic spin dynamics in the critical region above the T_S at T* offers a dynamic magnetic scattering mechanism for anisotropic electronic properties in the commonly referred "nematic phase".