Current-Induced Manipulation of the Exchange Bias in a Pt/Co/NiO Structure

Abstract

An experimental study of the phenomenon of electric current influence on the value and orientation of the exchange bias field (H EB) in the Pt/Co/NiO structure is carried out. Depending on the direction of the magnetization in a ferromagnet (FM) layer and the current pulse amplitude, the value of the H EB field can be changed repeatedly in the range of ±7.5 mT. A few experiments are performed to separate the contributions from two current-induced effects: (i) an injection of the spin current into an antiferromagnet layer (AFM) and (ii) Joule heating. As a result, we conclude that the modification in the H EB field during current pulse transmission in the Pt/Co/NiO structure is due to heating and the low value of Néel temperature (T N = 162 °C). This fact explains the absence of the exchange bias effect on the spin–orbit torque (SOT)-assisted magnetization switching. The most striking observation to emerge from the experimental data analysis is that depending on the initial spin configuration of the domain structure in the FM layer and the current pulse amplitude, the exchange bias can be changed locally. This opens up prospects for creating exchange-coupled FM/AFM structures with dynamically tuned parameters of the exchange bias, which can be used for the development of magnetic memory, neuromorphic, and logic devices based on magnetic nanosystems.

Resistive Memristor Coupled with Multilevel Perpendicular Magnetic States

“…36 It was found that in our Pt/Co/NiO devices, the temperature increased with applied voltage up to a critical temperature T crit of 335 K (see Supporting Information Figure S6), at which the RESET occurs. This value is far below the reported T N of a thin-film NiO (435−473 K) 25,43 and/or bulk NiO (∼525 K). 23 Based on these considerations, we can exclude the Joule heating effect from the mechanism that controls the EB through resistive switching.…”

Enhanced Spin–Orbit Torque Efficiency by the Insertion of a Thin NiO Underlayer in Pt/Co/Ta Films

“…Nevertheless, the use of metallic spin sink layers is generally discouraged due to the potential increase in energy consumption resulting from current shunting. Recently, antiferromagnetic insulators have gained attention for their capabilities in high-efficiency, electron-free spin current transmission. − Within this context, the insulating NiO film, with a high bulk Néel temperature of over 500 K, emerges as a notable candidate in spintronics. ,− Magnon-mediated magnetization switching was achieved with remarkable efficiency in the all-oxide heterostructure of SrRuO 3 /NiO/SrIrO 3 . Specifically, by inserting an insulating NiO layer within an in-plane magnetized Pt/NiO/CoFeB structure, the SOT efficiency of Pt can be significantly enhanced, potentially reaching the upper limit of the spin Hall angle.…”

Locally Reconfigurable Exchange Bias for Tunable Spintronics by Pulsed Current Injection

“…EB has been realized in a variety of systems, including nanoparticles, epitaxial films, and polycrystalline films. [8][9][10][11] The establishment of EB usually involves cooling (or growing) the FM/AFM heterostructure from an elevated temperature higher than the Néel temperature in the presence of a static bias magnetic field, resulting in uniform EB of the device elements on a wafer level. However, with the increasing demand in terms of integration and scalability of the devices, localized manipulation of EB becomes desirable for design and optimization of various spintronic devices.…”