Giant converse magnetoelectric effect in a multiferroic heterostructure with polycrystalline Co2FeSi

Abstract To overcome a bottleneck in spintronic applications such as those of ultralow-power magnetoresistive random-access memory devices, the electric-field control of magnetization vectors in ferromagnetic electrodes has shown much promise. Here, we show the giant converse magnetoelectric (CME) effect in a multiferroic heterostructure consisting of the ferromagnetic Heusler alloy Co 2 FeSi and ferroelectric-oxide Pb(Mg 1/3 Nb 2/3 )O 3 -PbTiO 3 (PMN-PT) for electric-field control of magnetization vectors. Using an in-plane uniaxial magnetic anisotropy of polycrystalline Co 2 FeSi film grown on PMN-PT(011), the nonvolatile and repeatable magnetization vector switchings in remanent states are demonstrated. The CME coupling coefficient of the polycrystalline Co 2 FeSi/PMN-PT(011) is over 1.0 × 10 −5 s/m at room temperature, comparable to those of single-crystalline Fe 1- x Ga x /PMN-PT systems. The giant CME effect has been demonstrated by the strain-induced variation in the magnetic anisotropy energy of Co 2 FeSi with an L 2 1 -ordered structure. This approach can lead to a new solution to the reduction in the write power in spintronic memory architectures at room temperature.