Magnetoelectric Properties of Pb Free Bi2FeTiO6: A Theoretical Investigation

TL;DR

This theoretical study explores the multiferroic properties of Pb-free Bi2FeTiO6, revealing its non-centrosymmetric structure, magnetic ordering, ferroelectric polarization, and strong magnetoelectric coupling potential.

Contribution

First-principles density functional theory analysis of Bi2FeTiO6's structure, magnetic, and ferroelectric properties, highlighting its multiferroic behavior and potential for electric field-controlled magnetic states.

Findings

Bi2FeTiO6 has a rhombohedral non-centrosymmetric structure.

It exhibits antiferromagnetic insulating behavior with a 0.3 eV bandgap.

The compound shows strong magnetoelectric coupling and a polarization of 48 μC/cm².

Abstract

The structural, electronic, magnetic and ferroelectric properties of Pb free double perovskite multiferroic Bi2FeTiO6 are investigated using density functional theory within the general gradient approximation (GGA) method. Our structural optimization using total energy calculations for different potential structures show a minimum energy for a non-centrosymmetric rhombohedral structure with R3 space group. Bi2FeTiO6 is found to be an antiferromagnetic insulator with C-type magnetic ordering with bandgap value of 0.3 eV. The calculated magnetic moment of 3.52 \mu_B at Fe site shows the high spin arrangement of 3d electrons which is also confirmed by our orbital projected density of states analysis. We have analyzed the characteristics of bonding present between the constituents of Bi2FeTiO6 with the help of calculated partial density of states and Born effective charges. The ground state of the nearest centrosymmetric structure is found to be a G-type antiferromagnet with half metallicity showing that by the application of external electric field we can not only get a polarized state but also change the magnetic ordering and electronic structure in the present compound indicating strong magnetoelectric coupling. The cation sites the coexistence of Bi 6s lone pair (bring disproportionate charge distribution) and Ti4+ d0 ions which brings covalency produces off-center displacement and favors a non-centrosymmetric ground state and thus ferroelectricity. Our Berry phase calculation gives a polarization of 48 \muCcm-2 for Bi2FeTiO6.