Temperature dependence of the ferroelectric and dielectric properties of the Ba_0.5Sr_0.5TiO₃/La_0.67Sr _0.33MnO₃ heterostructure

A ferroelectric and colossal-magnetoresistant material with a Ba _0.5Sr_0.5TiO₃ (BST)/La_0.67Sr _0.33 MnO₃ (LSMO) heterostructure was deposited epitaxially on (001) LaAlO₃ substrates through pulsed laser deposition. Measurements of the magnetic and ferroelectric properties show no obvious degradation of the LSMO layer after BST film deposition. For the BST film, as the temperature decreases from 300 to 20 K, both the remanent polarization and the coercive field increase monotonously up to 5.7 μC cm^-2 and 63.7 kV cm^-1, respectively. Meanwhile, the temperature dependence of the spontaneous polarization shows a second-order ferroelectric phase transition, and the Curie temperature is estimated to be about 220 K. Furthermore, in the temperature range from 20 to 300 K, the dielectric constant (E = 0) and the dielectric tunability (E = 200 kV cm ^-1) exhibit similar temperature dependences, and show maximum values of 1252 and 45.3% at 200 K, respectively.