Neutron Scattering Study on Spin Dynamics in Superconducting (Tl,Rb)2Fe4Se5

TL;DR

This study uses neutron scattering to analyze spin dynamics in superconducting (Tl,Rb)2Fe4Se5, revealing a localized spin model with specific exchange interactions that inform theories of magnetism and superconductivity in Fe-based materials.

Contribution

It provides detailed experimental data on spin-wave branches and determines key exchange constants, advancing understanding of magnetic interactions in this superconductor.

Findings

Spin-wave branches span 6.5 to 209 meV.

Spin dynamics fit a Heisenberg localized spin model.

Exchange constants constrain theoretical models.

Abstract

We observed in superconducting (Tl,Rb)2Fe4Se5 spin-wave branches that span an energy range from 6.5 to 209 meV. Spin dynamics are successfully described by a Heisenberg localized spin model whose dominant in-plane interactions include only the nearest (J1 and J1') and next nearest neighbor (J2 and J2') exchange terms within and between the tetramer spin blocks, respectively. These experimentally determined exchange constants would crucially constrain the theoretical viewpoints on magnetism and superconductivity in the Fe-based materials.