Pressure Induced Ferromagnetism in Cubic Perovskite SrFeO3 and BaFeO3

TL;DR

This study uses density functional theory to show that applying high pressure induces a transition from helical spin orders to ferromagnetism in cubic perovskite SrFeO3 and BaFeO3, aligning with experimental observations.

Contribution

It provides a theoretical prediction of pressure-induced ferromagnetism in SrFeO3 and BaFeO3 using DFT calculations, highlighting the role of lattice compression.

Findings

Phase transition to ferromagnetism at reduced lattice constants

Superexchange interaction becomes dominant under high pressure

BaFeO3 becomes a good metal under high pressure

Abstract

The spin order in cubic perovskite SrFeO3 and BaFeO3 under high pressure is studied by density functional theory (DFT) calculation with local spin density approximation plus Hubbard U (LSDA+U). At ambient pressure, A-type and G-type helical spin orders are almost degenerate in BaFeO3 whose lattice constant is 3.97{\AA} . When the lattice constant is reduced to 3.85 {\AA} which is same as the lattice constant of SrFeO3 at ambient pressure, G-type helical spin order becomes stable, being consistent with SrFeO3. This is because superexchange interaction is enhanced as compared with double exchange interaction. Phase transition from helical spin state to ferromagnetic state in both SrFeO3 and BaFeO3 takes place if the lattice constant is further reduced to 3.70 {\AA}. This is because reduced local spin moment weakens the contribution from superexchange interaction. Our result agrees with recent experimental result of BaFeO3 under high pressure. Additionally, our calculation predicts that half-metal BaFeO3 at ambient pressure will become a good metal under high pressure