Utilization of magnetoelectric effects in multiferroic materials hold great potential to fabricate nonvolatile memory devices with outstanding characteristics. In particular, organic thin memories are favorable because of their environment friendly nature, mechanical flexibility, and low fabrication cost. In this work, we have demonstrated a room temperature paradigm two level nonvolatile memory operation by exploiting the nonlinear magnetoelectric effects in flexible SmFeO 3 /P(VDF-TrFE) nanocomposite films using organic ferroelectric polymer (P(VDF-TrFE)) as a host matrix. Strong strain mediated interfacial interactions between ferromagnetic and ferroelectric phases in SmFeO 3 /P(VDF-TrFE) nanocomposite films allow electric field controlled magnetic switching. The maximum magnetoelectric coefficient (α) obtained is 45 mV cm −1 Oe 1− at H bias = 1 kOe and 16 mV cm −1 Oe 1− at H bias = 0 in electrically poled composite films (30% SmFeO 3 ). The experiments demonstrate that during seven operative cycles for 1500 s, the applied positive and negative electric fields can repeatedly switch states of α. Binary information is stored by using the states of α, rather than resistance, magnetization, and electric polarization, which is advantageous to overcome the drawback of destructive reading of polarization of ferroelectric random access memory. The magnetoelectric response and the required voltage for switching of α can be tuned by varying the magnetic phase fraction (SmFeO 3 nanoparticles) in nanocomposite films. Hence, the kind of nonvolatile memory using organic, flexible magnetoelectric SmFeO 3 /P(VDF-TrFE) nanocomposite films has excellent practical characteristics, that is, compactness, easy and fast speed reading/writing operation, and reduced power consumption.

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In this letter, studies on structural transitions and the effect of electric field poling on magnetoelectric (ME) properties in 0.65Pb (Mg1/3Nb2/3)O3-0.35PbTiO3 (PMN-PT)/NiFe2O4 (NFO) nanocomposites are reported. The composite illustrates dramatic changes in the NFO crystal structure across ferroelectric transition temperature [Curie temperature (Tc) ∼ 450 K] of PMN-PT, while pure NFO does not exhibit any structural change in the temperature range (300 K–650 K). Synchrotron based X-ray diffraction analysis revealed the splitting of NFO peaks across the Tc of PMN-PT in the PMN-PT/NFO composite. Consequently, the anomalies are observed in temperature dependent magnetization of the NFO phase at the Tc of PMN-PT, establishing ME coupling in the PMN-PT/NFO composite. Furthermore, the composite exhibits drastic modification in ME coupling under electrically poled and unpoled conditions. A large self-biased ME effect characterized by non-zero ME response at zero Hbias was observed in electrically poled composites, which was not observed in unpoled PMN-PT/NFO. These results propose an alternative mechanism for intrinsic converse ME effects. The maximum magnetoelectric output was doubled after electrical poling. The observed self-biased converse magnetoelectric effect at room temperature provides potential applications in electrically controlled memory devices and magnetic flux control devices.

In this work, a well-ordered array of multiferroic magnetoelectric (ME) dot-like nanostructures of Pb(Mg1/3Nb2/3)O3]0.65–[PbTiO3]0.35 (PMN-PT)/NiFe2O4 is explored for high density and low power consuming memory devices. Ordered arrays of ferromagnetic NiFe2O4 nanodots underneath a ferroelectric PMN-PT layer were fabricated using silicon nitride based stencil masks and pulsed laser deposition techniques. The piezo-response and magnetic force microscopy (PFM) measurements reveal coexistence of magnetic and ferroelectric domains in PMN-PT/NiFe2O4 films at room temperature. The ferroelectric polarization can be switched with the electrically biased PFM tip. The ME coupling is evident in the PMN-PT/NiFe2O4 films, which is attributed to the transfer of the elastic strain from PMN-PT to NiFe2O4. The PMN-PT/NiFe2O4 nanodot films exhibit enhanced ME coupling coefficient (α) as compared to continuous bilayer PMN-PT/NiFe2O4 films, owing to the superior strain transfer efficiency in nanodot heterostructures. The nanodot films demonstrate electric-field controlled nonvolatile switching of α, which can be used to store binary information in memory devices, holding all the advantages of ferroelectric random access memory but overcoming the major disadvantage of destructive reading of polarization. The results reveal a versatile approach for fabrication of well-ordered nanodot arrays for low power consuming, high-density ME device applications.