Ferromagnetic, Ferroelectric, and Optical Modulated Multiple Resistance States in Multiferroic Tunnel Junctions

In data storage devices, spin, ferroelectric, or optical indices have been utilized as information carriers, and the binate couplings among the three parameters are explored to increase the resistance states and resultant data-density. However, studies holding all of the three information indices are still blank, where the increasing number of information carriers from previous two to three provides opportunities for inducing novel phenomena and distinct resistance states. In this work, using the spin-electron-photon resolved theory, we demonstrate the feasibility of spin, ferroelectric, and optical interactions, which are further detected by a spin- and ferroelectric-modulated photovoltaic effect in La_2/3Sr_1/3MnO₃/BiFeO₃/Fe₄N multiferroic tunnel junctions (MFTJs). Moreover, based on the spin- and ferroelectric-induced four resistance states in MFTJs, the special photovoltaic effect shall split each resistance state into light-on and light-off switching states, which finally lead to multiple resistance states. Besides, nearly 100% spin-polarized photocurrent and large tunneling magnetoresistance (electroresistance) are realized in these MFTJs. These results reveal that interacted spin, ferroelectric, and optical indices can simultaneously serve as information carriers in storage devices, which provide guidance for developing efficient data memories.