Search for Magnetoelectric Coupling at the ⁵⁷Fe/Hf0.5Zr0.5O2 Interface Using Operando Synchrotron Mössbauer Spectroscopy

Multiferroic materials with coexisting ferroelectric and ferromagnetic orders have attracted much attention due to the magnetoelectric coupling opening alternative prospects for electronic devices. Composite multiferroics containing separate ferroelectric and ferromagnetic components are a promising alternative to the single-phase counterparts. Composite multiferroic structures comprising HfO-based ferroelectrics are potentially feasible for technological applications. Here, this study reports on the experiments aiming at the manifestation of magnetoelectric coupling at Fe/HfZrO (HZO) interface. Using synchrotron based Fe Mössbauer spectroscopy technique in operando, this study probes element-selectively the local magnetic properties of a nanometer-thick enriched Fe marker layer in functional Pt/Fe/HZO/TiN capacitors and demonstrates the evidence of the ferroelectric polarization effect on the ?-Fe magnetic response. Besides ?-Fe exhibiting a magnetoelectric coupling, both ferromagnetic and superparamagnetic FeO components are found in the Mössbauer spectra, apparently originating from the oxygen or OH ions penetrating ultrathin Pt overlayer during crystallization annealing of HZO. The observed effect as well as the electronic band lineup of the Fe/HZO interface elucidated from synchrotron based hard X-ray photoemission spectroscopy measurements are interpreted in terms of charge-mediated magnetoelectric coupling at the Fe/HfO interface driven by ferroelectric HZO polarization reversal.