Tetragonal tungsten bronze Ba2EuFeNb4O15–based composite thin films multiferroic at room temperature

Abstract

Epitaxial c-oriented thin films of tetragonal tungsten bronze Ba2EuFeNb4O15 have been deposited on Nb-doped SrTiO3(100) single crystal substrates by pulsed laser deposition. The structural investigation established that the unit cell of Ba2EuFeNb4O15 thin films is rotated in the plane of the film by ±18° with respect to the SrTiO3:Nb substrate unit cell. The ferroelectric nature of the epitaxial Ba2EuFeNb4O15 films has been established macroscopically by measuring ferroelectric hysteresis loops at room temperature. The electromechanical properties investigated microscopically allowed demonstrating the hysteretic variation of the piezoelectric coefficient with an applied electric field, confirming that the ferroelectric nature of the studied thin films was conserved down to the nanoscale. A magnetic secondary phase was observed and its ferromagnetic hysteresis loop demonstrated the achievement of composite thin films based on tetragonal tungsten bronze structure, which are multiferroic at room temperature.