First-principles study of magnetic properties in Fe-ladder compound BaFe2S3

TL;DR

This study uses first-principles calculations to analyze the magnetic, structural, and electronic properties of BaFe2S3, revealing the magnetic ground state, exchange interactions, and pressure-induced insulator-metal transition.

Contribution

It provides a detailed theoretical understanding of the magnetic structure and electronic behavior of BaFe2S3, including the effects of pressure on its phase transitions.

Findings

The most stable magnetic alignment is ferromagnetic along the rung and antiferromagnetic along the leg.

The calculated energy gap matches experimental observations.

Pressure induces an insulator-metal transition.

Abstract

We study the magnetic, structural, and electronic properties of the recently discovered iron- based superconductor BaFe2S3 based on density functional theory with the generalized gradient approximation. The calculations show that the magnetic alignment in which the spins are coupled ferromagnetically along the rung and antiferromagnetically along the leg is the most stable in the possible magnetic structure within an Fe-ladder and is further stabilized with the periodicity char- acterized by the wave vector Q=(pi,pi,0), leading to the experimentally observed magnetic ground state. The magnetic exchange interaction between the Fe-ladders creates a tiny energy gap, whose size is in excellent agreement with the experiments. Applied pressure suppresses the energy gap and leads to an insulator-metal transition. Finally, we also discuss what type of orbitals can play crucial roles on the magnetic and insulator-metal transition.