Lattice mismatch induced strained phase for magnetization, exchange bias and polarization in multiferroic BiFeO3

Abstract

We have utilized the lattice mismatch between two adjacent nanocrystals in polycrystalline BFO ceramics to introduce a layer of highly strained BFO phase by taking advantage of crystal growth course. Therefore, a spin-valve like structure has been fabricated that consists of ferromagnetic phase (highly strained BFO phase)/antiferromagnetic phase (bulk BFO nanoparticles), without any substrates or alloy layers. BFO ceramics can present an exchange biasing effect ((|H_EB|) ∼ 36 Oe) with an enhanced magnetic moment (M_s ∼ 0.11 μ_B Fe⁻¹) and in addition saturated polarization (2P_r ∼ 57.4 μC cm⁻²) at room temperature. A low working electric field (E_c ∼ 4.8 kV cm⁻¹) shows an advantage of low energy consumption in application. These results imply that there is potential for room temperature applications of single phase BFO with exchange biasing, enhanced magnetization and saturated polarization.