Colossal Magnetoresistive Switching Induced by d0 Ferromagnetism of MgO in a Semiconductor Nanochannel Device with Ferromagnetic Fe/MgO Electrodes

Abstract

AbstractExploring potential spintronic functionalities in resistive switching (RS) devices is of great interest for creating new applications, such as multifunctional resistive random‐access memory and novel neuromorphic computing devices. In particular, the importance of the spin‐triplet state of cation vacancies in oxide materials, which is induced by localized and strong O–2p on‐site Coulomb interactions, in RS devices has been overlooked. d0 ferromagnetism sometimes appears due to the spin‐triplet state and ferromagnetic Zener's double exchange interactions between cation vacancies, which are occasionally strong enough to make nonmagnetic oxides ferromagnetic. Here, for the first time, anomalous and colossal magneto‐RS (CMRS) with very high magnetic field dependence is demonstrated by utilizing an unconventional RS device composed of a Ge nanochannel with all‐epitaxial single‐crystalline Fe/MgO electrodes. The device shows colossal and unusual behavior as the threshold voltage and ON/OFF ratio strongly depend on a magnetic field, which is controllable with an applied voltage. This new phenomenon is attributed to the formation of d0‐ferromagnetic filaments by attractive Mg vacancies due to the spin‐triplet states with ferromagnetic double exchange interactions and the ferromagnetic proximity effect of Fe on MgO. The findings will allow the development of energy‐efficient CMRS devices with multifield susceptibility.