Piezoelectric and ferroelectric response enhancement in multiferroic YCrO3 films by reduction in thickness

• Piezo-ferroelectric responses were induced in YCrO3 films by thickness reduction.
• The films, grown by sputtering at room temperature, were post-annealed at 900 °C.
• Performance was improved by the reduction of charge accumulation.
• Charge accumulation was diminished by the more homogeneous growth.
• Ferromagnetism is also present, therefore multiferroicity is achieved.

A study of the piezoelectric response and polarization switching of YCrO3 films as function of thickness, is presented. The films, 20 to 180 nm thick, were deposited on Pt/TiO2/Si substrates by r.f. sputtering at room temperature, and then annealed at 900 °C for 1 h in air. Better grain coalescence and reduction of charge accumulation at grain boundaries was observed in thinner films, leading to the appearance and enhancement of the piezoresponse. A piezoelectric coefficient of d33~6.4 pm/V and a coercive voltage of Vc~12.5 V were obtained in the 20 nm film, which also showed a magnetic hysteresis loop. Therefore, while maintaining the ferromagnetic behavior, ferroelectricity, hence multiferroicity, is induced in YCrO3 when film thickness is reduced to 20 nm.