First-principles characterization of ferromagnetism in N-doped SrTiO3 and BaTiO3

TL;DR

This study uses first-principles calculations to analyze how nitrogen doping induces ferromagnetism in SrTiO3 and BaTiO3, revealing the conditions for magnetic ordering and explaining experimental observations.

Contribution

It provides a detailed first-principles analysis of N-doped SrTiO3 and BaTiO3, identifying the doping conditions that lead to ferromagnetism and explaining experimental findings.

Findings

N doping induces half-metallicity and magnetic moments.

Strong ferromagnetic coupling occurs at short N-N distances.

Ferromagnetism diminishes when N-N distance exceeds 7 Å.

Abstract

The spin-polarization and magnetic coupling character of N-doped SrTiO3 and BaTiO3 are studied through first-principles calculations. The substitutional N doping at O sites leads to a half-metallic property and produces a magnetic moment of 1.0 {\mu}B. The magnetic interaction between the nearest and next-nearest N dopants results in a strong ferromagnetic coupling. When the distance between the N dopants is larger than 7 {\AA}, the ground state of the system tends to be paramagnetic. A nitrogen-concentration threshold to produce the ferromagnetism is estimated. The calculated results give a good explanation for the experimentally observed ferromagnetism in N-doped SrTiO3 and BaTiO3.