“…In particular, ferroelectric-related films with DC electric field dependent dielectric permittivity are used to develop frequency-agile electronic devices such as varactors, microwave filters, resonators, voltage-controlled oscillators, and phase shifters, besides passive components [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. For these applications, in addition to the high tunability of dielectric permittivity, the films should have low loss and reduced permittivity values [15][16][17]. Since the tunability of a ferroelectric material is maximized near its Curie point, incipient ferroelectrics such as SrTiO 3 (ST) are useful at cryogenic temperatures (T), whereas regular ferroelectrics such as BaTiO 3 are more suitable above room T [2,15].…”