Multiferroic materials, which exhibit simultaneous ferroelectric (FE) and magnetic (ferro- or antiferromagnetic) orders with coupling (Magnetoelectric Effect (ME)) between them, are been exploiting for miniaturization, high integration density and multi-functionality devices. Specially, compositing various room-temperature FM and FE materials provide an effective strategy to achieve the strong room-temperature magnetoelctric coupling in the multiferroic materials. This approach combines the advantages of conventional magnetic random access memory (MRAM) and ferroelectric random access memory (FeRAM), while avoiding the short-comings of these two storage techniques. Therefore, this technique has the potential for the low-power cost, non-volatility, and high-density storage technology.
Here, we reports the study of strain-control of resistance in the (011)-La2/3Sr1/3MnO3 (LSMO)/0.7Pb(Mg2/3Nb1/3)O3-0.3PbTiO3 (PMN-PT) epitaxial heterostructures. We used high resolution X-ray reciprocal space mapping (RSM) LSMO (103) peak in Hefei Light Source (U7B). The result in Fig. 1(a) shows that the LSMO is epitaxially grown on the PMN-PT substrate and the [100] direction is parallel with that of the PMN-PT substrate. The resistance along the [100] direction is measured as schematically drawn in the Fig. 1(b) at room temperature.

Fig. 1 (a) reciprocal space mapping for the (103) peaks. (b) The field-effect transistor structure for the transport measurement at room temperature.

The transport measurement results in Fig. 2(a) and (b) indicate that the resistance can be switched non-volatilely by electric field between “0” and “1”, “0” and “2” states. Moreover, the pulse electric field with the certain cycling sequence can realize the multi-state memory, as shown in Fig. 2(c). The “0”, “1” and “2” states are simultaneously switched among them. This result is attributed to the electric-field-induced non-volatile strain in the LSMO film. Consequently, the non-volatile resistance even with multi states is attained in this multiferroic heterostructures. The above results have been published on Applied Physics Letters 102, 033501 (2013).

Fig. 2 Strain-control of non-volatile resistance switching between “0” and “1” in (a), “0” and “2” in (b), “0”, “1” and “2” in (c).