Magnetic properties of iron pnictides from spin-spiral calculations

TL;DR

This study uses spin-spiral calculations to analyze how magnetic properties and exchange interactions in iron pnictides vary with wave-vector and doping levels, revealing shifts in magnetic order with doping.

Contribution

It provides a detailed computational analysis of magnetic energy landscapes and exchange interactions in iron pnictides as functions of doping and wave-vector, highlighting incommensurate magnetic states.

Findings

Stripe antiferromagnetic order is favored in undoped compounds.

Electron doping induces incommensurate magnetic states at low doping levels.

Hole doping maintains stripe order down to significant doping levels.

Abstract

The wave-vector (q) and doping dependences of the magnetic energy, iron moment, and effective exchange interactions in LaFeAsO, BaFe2As2, and SrFe2As2\ are studied by self-consistent LSDA calculations for co-planar spin spirals. For the undoped compounds, the calculated total energy, E(q), reaches its minimum at q corresponding to stripe anti-ferromagnetic order. In LaFeAsO, this minimum becomes flat already at low levels of electron-doping and shifts to an incommensurate q at delta=0.2, where delta is the number of additional electrons (delta>0) or holes (delta<0) per Fe. In BaFe2As2 and SrFe2As2, stripe order remains stable for hole doping down to delta=-0.3. Under electron doping, on the other hand, the E(q) minimum shifts to incommensurate q already at delta=0.1.