Magnetic Tunnel Junctions Based on Ferroelectric Hf0.5Zr0.5O2 Tunnel Barriers

Ferroelectric tunnel barriers in between two ferromagnetic electrodes (multiferroic tunnel junctions, or MFTJs) hold great promise for future microelectronic devices. Here, we utilize Hf0.5Zr0.5O2 (HZO) tunnel barriers with an ultralow thickness of only 2 nm, epitaxially grown on La0.7Sr0.3MnO3 ferromagnetic bottom electrodes and with cobalt top electrodes. Both tunneling electroresistance and tunneling magnetoresistance effects are observed, demonstrating four nonvolatile resistance states in HZO-based junctions. The large band gap and excellent homogeneity of the HZO tunnel barriers enable a high yield of working devices, as well as devices with sizes of tens of micrometers. This allows working with fixed electrodes, as opposed to the use of scanning probes, bringing MFTJs closer to applications.