Abstract
Resistive Switching in oxides has offered new opportunities for developing resistive random access memory (ReRAM) devices. Here we demonstrated bipolar Resistive Switching along with magnetization switching of cobalt ferrite (CFO) thin film using Al/CFO/FTO sandwich structure, which makes it a potential candidate for developing future multifunctional memory devices. The device shows good retention characteristic time (>104 seconds) and endurance performance, a good resistance ratio of high resistance state (HRS) and low resistance state (LRS) ~103. Nearly constant resistance values in LRS and HRS confirm the stability and non-volatile nature of the device. The device shows different conduction mechanisms in the HRS and LRS i.e. Schottky, Poole Frenkel and Ohmic. Magnetization of the device is also modulated by applied electric field which has been attributed to the oxygen vacancies formed/annihilated during the voltage sweep and indicates the presence of valence change mechanism (VCM) in our device. It is suggested that push/pull of oxygen ions from oxygen diffusion layer during voltage sweep is responsible for forming/rupture of oxygen vacancies conducting channels, leading to switching between LRS and HRS and for switching in magnetization in CFO thin film. Presence of VCM in our device was confirmed by X-ray Photoelectron Spectroscopy at Al/CFO interface.
Highlights
Using magnetic oxides in resistive random access memory (ReRAM) devices can open a new door of memory devices where the magnetic properties of the device can be modulated along with the resistive switching of the device
In the positive voltage sweep, the resistance of the device suddenly decreases near 1.1 volt and the device switches into Low Resistance State (LRS) from High Resistance State (HRS)
To understand the exact role of oxygen vacancies in the bipolar resistive switching mechanism in our device, we investigated the magnetic properties of the device in the Pristine State (PS), Low Resistance State (LRS) and High Resistance State (HRS)
Summary
Using magnetic oxides in ReRAM devices can open a new door of memory devices where the magnetic properties of the device can be modulated along with the resistive switching of the device. Electric field modulation of magnetization and RS effect in some magnetic oxides has been investigated, but the mechanism of RS effect and its correlation with the magnetization have not been fully understood[11]. Most of the reports on RS properties of stoichiometric magnetic oxides have used noble (chemically inert) material as an electrode, which generally leads to a unipolar behaviour of the device[24,26,27,28]. We present a multifunctional Resistive Switching memory device using CFO thin film with aluminum (a chemically active metal) as top electrode and having a simple structure (Al/CoFe2O4/FTO(fluorine doped tin oxide)), whose magnetic properties can be modulated along with the switching in the resistance states only by voltage stimulus. A possible model for explaining the behavior of the device in different states have been proposed
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