Zaulychny V. The investigation of size effects in thin ferroelectric films allowing for influence of electrodes

Using phenomenological theory of Ginsburg - Landau the systematic research of influencing of electrodes is conducted on size effects and properties of ferroelectric thin film. The generalized model of ferroelectric condenser is offered on the base of nanosized ferroelectric film and with two electrodes, one of which is sawed on substrate. The features of behavior of the electric field are analyzed in different electrodes, namely in metallic and semiconducting. Contribution of each electrode is calculated to free energy of the whole system, that allows the subsequent search for solution of Euler - Lagrange equation and to obtain this solution by the method of direct variation. The behavior of the field of depolarization is found inside ferroelectric film. Analytical dependences of the basic properties of the ferroelectric film are found depending on parameters of electrodes, temperature and material of the film. Existence of the critical values of electrode's parameters is found. If the value of the parameter is higher then critical one, the existence of ferroelectric phase is impossible. Phase diagrams, which describe the phase transition induced by electrodes, are built. Analytical dependences of the basic parameters of the phase transition are also represented in connection with the basic parameters of electrodes and film.