Nonvolatile Multilevel States in Multiferroic Tunnel Junctions

TL;DR

This paper demonstrates multilevel resistance states in multiferroic tunnel junctions controlled by ferroelectric polarization, enabling potential multi-state memory devices with nonvolatile electrical control.

Contribution

It reveals the role of mixed ferroelectric states in achieving accumulative electrical modulation of resistance in MFTJs, a novel approach for multi-state memory.

Findings

Multilevel resistance states achieved via ferroelectric domain reversal.

Nonvolatile control of resistance states through ferroelectric polarization.

Separate contributions from two ferroelectric channels in PZT interlayer.

Abstract

Manipulation of tunneling spin-polarized electrons via a ferroelectric interlayer sandwiched between two ferromagnetic electrodes, dubbed Multiferroic Tunnel Junctions (MFTJs), can be achieved not only by the magnetic alignments of two ferromagnets but also by the electric polarization of the ferroelectric interlayer, providing great opportunities for next-generation multi-state memory devices. Here we show that a La0.67Sr0.33MnO3 (LSMO)/PbZr0.2Ti0.8O3(PZT)/Co structured MFTJ device can exhibit multilevel resistance states in the presence of gradually reversed ferroelectric domains via tunneling electro-resistance and tunneling magnetoresistance, respectively. The nonvolatile ferroelectric control in the MFTJ can be attributed to separate contributions arising from two independent ferroelectric channels in the PZT interlayer with opposite polarization. Our study shows the dominant role of "mixed" ferroelectric states on achieving accumulative electrical modulation of multilevel resistance states in MFTJs, paving the way for multifunctional device applications.