Topological multiferroics

Abstract

Based on first-principles calculations, we explore an unconventional type of multiferroicity obtained via magnetic doping of wide-gap layered-perovskite ferroelectrics of the family A${}_n$Ti${}_n$O${}_{3n+2}$. Using the $n=4$ member La${}_2$Ti${}_2$O${}_7$ as home base, we substitute 3d atoms for Ti. The highlights of our results are that (1) low-concentration substitution of Ti by V produces robust unidirectional ferromagnetic (FM) order, resulting in a small-gap proper multiferroic, which in addition has electrically switchable magnetization, and (2) the isovalent substitution of Mn for Ti produces multiferroicity with weak FM order due to canting of antiferromagnetic Mn spins, and larger-than-usual linear magnetoelectric coupling.

Keywords:

• ferroelectricity
• magnetism
• multiferroicity
• doping

Acknowledgements

Computing resources provided in part by CASPUR Rome, and Cybersar Cagliari.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

Work supported in part by MIUR-PRIN project ‘Oxide’ and by grants from CINECA and from Fondazione Banco di Sardegna.