Multiferroic behavior of CoFe1.6Al0.4O4 spinel thin films

•Room temperature multiferroicity is obtained in CoFe1.6Al0.4O4 thin films.•The films exhibit well defined ferroelectric and piezoelectric properties.•Atomic orderings and structural deformation might induce the ferroelectric order. Here a single-phase multiferroic spinel CoFe1.6Al0.4O4 is presented which exhibits ferrimagnetic and ferroelectric properties at room temperature. The CoFe1.6Al0.4O4 films exhibit spinel structure with Fd 3- m space group. The study of the magnetic behaviors prove the ferrimagnetic nature of the compound. The CoFe1.6Al0.4O4 films exhibit typical ferroelectric hysteresis with remnant polarization of 1.0 μC/cm2 and significant piezoresponse displacement at room temperature, which suggest that the ferroelectric order is presented in the spinel films. The ferroelectric order in the CoFe1.6Al0.4O4 spinel likely originates from the possible atomic orderings in cationic sublattices and local deformation induced by the substitution of Al ions at the sublattices of CoFe2O4. Our result provides contributions to the development of single phase multiferroics.