Dielectric tunability analysis of pyrochlore Bi1.5Zn1.0Nb1.5O7 using epitaxial films on pyrochlore Bi2Ru2O7 conductive layers

To investigate the origin of the dielectric tunability, epitaxial Bi1.5Zn1.0Nb1.5O7 (BZN) films are grown on a pyrochlore Bi2Ru2O7 conductive layer by metal-organic chemical vapor deposition. The dielectric tunability is 41% at 2.5 MV/cm in the temperature range of 100–300 K, but is significantly suppressed below ∼100 K, suggesting that the dielectric tunability of the BZN film is due to random dipole contributions. However, a non-negligible dielectric tunability remains even at 4 K, implying that additional factors, such as phonons, contribute to the tunability.