Dielectric properties of Bi 1-xLa xFeO 3 thin films

Multiferroics on the basis of BiFeO 3 with spatially-modulated anti-ferromagnetic structure were investigated. The compounds BiFeO 3 widely and intensively are investigated as model objects for research of the mechanism of interaction between electric and magnetic subsystems, and for their possible use in spin electronics. Possibility of electric management of magnetization of a material at a room temperature is of interest from the point of view of its use in elements of computer memory with electric record and magnetic reading. The purpose of the investigation is to define the change in magnetoelectric interaction as a result of a variation of an antisymmetric exchange and to investigate the mechanism of low-temperature and high-temperature anomalies of dielectric permeability at bismuth replacement by lanthanum. It’s important to establish magnetoelectric properties of disorder system with random distribution of a constant of magnetoelectric interaction. On films of La xBi 1-xFeO 3 measurements of dielectric permeability, a tangent of angle of losses in the range of temperatures 100 K 5 Hz are defined. At approach to ferroelectric transition dielectric permeability and dielectric losses are sharply increased. At a temperature 835 K the changes in crystal structure attributed to transition from rhombohederal to the orthorhombic phase was found. In the vicinity of magnetic phase transition the anomalies in temperature behavior of dielectric permeability are absent. Bismuth replacement by lanthanum leads to small increase in magnetocapacity, in comparison with pure BiFeO 3. Magnetocapacity increases in external electric field, passes through a maximum and falls with growth of temperature.