Ultralow energy switching with spin polarized magneto-electric properties of co-doped cubic phase BFO: A first-principles study

Abstract

Bismuth ferrite BiFeO3 (BFO) is one of the most studied multiferroic materials. The coupling between electric polarization and magnetization provides the potential for the next-generation low-switching memory devices. To enhance the switching functionality of BFO, the effect of lanthanum (La) at A-site and cobalt (Co) at B-site as mono- and co-dopants on spin-polarized electronic structure, ferroelectric polarization, and magnetic properties are investigated using the first principles. An increase in the energy states density is observed with the introduction of La and Co atoms, which change the band gap in the spin-down state. La-doping significantly enhances the dielectric constant, whereas the dielectric constant for La and Co co-doped system decreases. Enhancement in the magnetic moment (µB)is detected on introducing Co atoms in BFO as mono- and co-dopant due to the combined involvement of La and Co, which destroy the cycloidal spin structure and activate the hidden spin. The high spin polarization of 87.08 % and linear Edelstein effect of 1.45 ×10–9 m/V are observed in La and Co co-substituted system. The ferroelectric polarization of La and Co co-doped BFO decreased (0.079 C/m2) significantly and has shown ultralow switching energy 0.52 aJ for magneto-electric spin-orbit (MESO) RAM capacitor.