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We demonstrate a memory device with bias electric field-manipulated multilevel resistance states based on ultra-thin and small area Fe70Ga30 (FeGa) films grown on BaZr0.2Ti0.8O3-0.5Ba0.7Ca0.3TiO3(BZT-0.5BCT) ferroelectric films. Studies have shown that BZT-0.5BCT ferroelectric films exhibit good ferroelectric properties with saturated polarization of 11.3 µC/cm2 and excellent piezoelectric properties with displacement up to 70 Å. A coercive field of 91 Oe is derived from the magnetic hysteresis loop of BZT-0.5BCT/FeGa composite films. Local ferroelectric domain and ferromagnetic domain structures have been probed, which confirm the multiferroicity of the composite films. By applying the bias electric field along the thickness of the films, current–voltage (I–V) behaviors of the FeGa films on the BZT–BCT films can be modulated, and multiple resistance states are generated. Based on the analysis of polarization switching behavior and the electrical transport characteristics, we ascribe this bias voltage modulation of the resistance state to strain-mediated converse magnetoelectric effect, interface bonding effect, and interface charge-co-mediated behaviors. This work suggests a promising approach for exploring multilevel and multifunctional data storage in multiferroic materials. [ABSTRACT FROM AUTHOR]

• Room temperature multiferroicity is obtained in CoFe 1.6 Al 0.4 O 4 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 CoFe 1.6 Al 0.4 O 4 is presented which exhibits ferrimagnetic and ferroelectric properties at room temperature. The CoFe 1.6 Al 0.4 O 4 films exhibit spinel structure with Fd 3 - m space group. The study of the magnetic behaviors prove the ferrimagnetic nature of the compound. The CoFe 1.6 Al 0.4 O 4 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 CoFe 1.6 Al 0.4 O 4 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 CoFe 2 O 4. Our result provides contributions to the development of single phase multiferroics. [ABSTRACT FROM AUTHOR]