DIELECTRIC THIN FILM, DIELECTRIC THIN FILM ELEMENT, PIEZOELECTRIC ACTUATOR, PIEZOELECTRIC SENSOR, HEAD ASSEMBLY, HEAD STACK ASSEMBLY, HARD DISK DRIVE, PRINTER HEAD AND INKJET PRINTER DEVICE

Provided is a dielectric thin film including a metal oxide. The metal oxide includes bismuth, sodium, barium, and titanium, at least a part of the metal oxide is a tetragonal crystal having a perovskite structure, and a (100) plane of at least a part of the tetragonal crystal is oriented in a normal direction do of a surface of the dielectric thin film