Multiferroic materials with coexisting ferroelectric and ferromagnetic orders have attracted much attention due to the magnetoelectric (ME) coupling opening prospects for alternative multifunctional electronic devices. Switching magnetization by applied electric rather than magnetic field or spin-polarized current requires much less energy, making multiferroics promising for memory and logic applications. Due to a limited number of single-phase multiferroic compounds operating at room temperature, composite multiferroics containing ferroelectric and ferromagnetic components have been considered as viable alternatives. Moreover, it was shown that composite multiferroic materials often have much larger magnetoelectric coupling effect compared to their single-phase counterparts.
The recently emerged class of polycrystalline doped HfO2-based ferroelectric thin films, which are compatible with the modern Si technology, is a promising ferroelectric component in composite multiferroic heterostructures and it is therefore crucial to explore the ME effect at the ferroelectric/ferromagnetic interface in the heterostructures comprising doped HfO2. In this respect, a strong charge-mediated magnetoelectric coupling at the interface between classical ferromagnetic metal – Ni and ferroelectric HfO2has been recently predicted by theoretical modelling.
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Image: Schematic drawing of a single capacitor device structure used in operando XAS/XMCD and HAXPES/MCDAD measurements with EELS (Electron energy loss spectroscopy) map of Co, Ni and O. Polarization vs. voltage hysteresis loop at RT and LT (left) and MOKE (right) of Au/Co/Ni/HZO/W sample are also shown in figure.
Credit: Elettra