Enhancement of multiferroic properties in Bi0.92Ho0.08Fe0.97Mn0.03O3/Zn0.5Ni0.5Fe2O4 bilayered thin films by tunable schottky barrier and interface barrier

摘要

The Bi(0.92-x)Ho(0.08)A(x)Fe(0.97)Mn(0.03)O(3)/Zn0.5Ni0.5Fe2O4 (BHAFMO/ZNFO, A = Ca, Sr and Ba) bilayered thin films were deposited on FTO/glass substrates by using the chemical solution deposition method. The structure, leakage current and multiferroic properties were investigated. The results indicate that the increase of oxygen vacancies in the BHAFMO/ZNFO films lead to the increase of Schottky barrier, which is beneficial to the bulk limiting conduction mechanism ( Ohmic and space-charge-limited-conduction (SCLC)). But the increase of Schottky barrier also leads to the polarization relaxation of BHAFMO/ZNFO films, and domain switching is more difficult. These indicate that the concentration and migration of oxygen vacancies can be controlled by ions doped BHFMO/ZNFO films with different ionic radii. Adjustment of the interface barrier and Schottky barrier by controlling the oxygen vacancies could not only change the conduction mechanism, but also adjust the ferroelectric domain switching to influence ferroelectric polarization. Because the structure is close to the morphotropic phase boundary (MPB), the substitutional ionic radius is larger than that of Bi3+, and the concentration of oxygen vacancies is low, so the BHSrFMO/ZNFO film exhibits excellent ferroelectric properties (the remnant polarization (P-r) = 82.1 mu C/cm(2) and the coercive field (E-c) = 566 kV/cm). (C) 2018 Elsevier B.V. All rights reserved.