Dielectric characteristics of heteroepitaxial Sr$_{0.60}$Ba$_{0.40}$Nb$_2$O$_6$ thin films grown on a Pt(001)/MgO(001) substrate

The structure, surface microstructure, dielectric and ferroelectric characteristics of thin films of barium-strontium niobate Sr$_{0.60}$Ba$_{0.40}$Nb$_2$O$_6$ (SBN60) grown on a Pt(001)/MgO(001) substrate have been studied. It is shown that the films are unalloyed, monocrystalline, and by the nature of changes in the dielectric permittivity ($\varepsilon'$ and $\varepsilon''$) from the temperature and frequency of the measuring electric field, they are relaxor ferroelectrics. It is established that in the investigated film the Burns temperature is 475 K, the Vogel–Fulcher temperature is 367 K, and in the vicinity of $T$ = 150 K there is a phase transition between two ferroelectric phases. It is shown that at room temperature, depending on the electric field strength, the prevailing charge transport mechanisms in SBN60 films are Poole–Frenkel emission and space charge limited current. The reasons for the revealed patterns are discussed.