Multiferroic properties of Aurivillius phase Bi₆Fe_2−<i>x</i>Co_<i>x</i>Ti₃O₁₈ thin films prepared by a chemical solution deposition route

Abstract

The magnetic and ferroelectric properties of Co-doped Bi6Fe2Ti3O18 thin films Bi6Fe2−xCoxTi3O18 (BFCTO) (0 ≤x≤ 1) are investigated. The coexistence of room-temperature ferromagnetism and ferroelectricity is observed in BFCTO thin films. The x = 0.6 sample exhibits a higher remnant magnetization Mr of 8.41 emu/cm3 and a remnant polarization Pr of 17.6 μC/cm2 compared with other BFCTO thin films. The ferromagnetism can be ascribed to the spin canting of Fe- and Co-based sublattices via the Dzyaloshinskii-Moriya interaction [I. Dzyaloshinsky, J. Phys. Chem. Solids 4, 241 (1958); T. Moriya, Phys. Rev. 120, 91 (1960)]. The change in the remnant polarization is discussed in terms of the variation of grain size and oxygen vacancies caused by Co-doping.