Write Margin Analysis of Spin-Orbit Torque Switching Using Field-Assisted Method
Journal
IEEE Journal on Exploratory Solid-State Computational Devices and Circuits
Journal Volume
5
Journal Issue
2
Pages
173-181
Date Issued
2019
Author(s)
Abstract
Switching dynamics of perpendicular magnetic tunnel junction (MTJ) driven by spin-orbit torque (SOT) are investigated by the Landau-Lifshitz-Gilbert (LLG)-based physical model considering the temperature dependence. The field-Assisted switching method is proposed to develop the reliable sub-ns writing of SOT-magnetoresistive random-Access memory (SOT-MRAM) by removing the plateau time. The conventional method of SOT-MTJ requires the large write current, leading to the area increase of access transistors and the penalty of memory density. The write current and the switching time of SOT-MTJ can be efficiently reduced at the same time by our field-Assisted method using the enhanced magnetic field. The magnetic field can be provided by the Co magnetic hard mask above the MTJ. Considering an SOT-MRAM array, the surrounded Co metals have the insignificant influence of stray magnetic field on an MTJ at the center. With the write time of 0.2 ns, the 60% reduction of write current is achieved by our field-Assisted method compared to the conventional method. The required write current for the SOT switching decreases with the increasing temperature due to the lowering of thermal stability factor. The write Shmoo plots are further analyzed to calculate the write current margin at the various working temperature. The write time of 0.2 ns exhibits the narrow margin of write current ( 2.6~\mu \text{A} ) in the temperature range from 25 °C to 85 °C, while the write time of 0.8 ns has the wide write margin of 102~\mu \text{A}. The switching behavior and the write margin are also sensitive to the magnetic field. ? 2014 IEEE.
Subjects
Failure analysis; Magnetic fields; Magnetic storage; MRAM devices; Spin dynamics; Spintronics; Temperature distribution; Tunnel junctions; Conventional methods; Increasing temperatures; Magnetic memory; Magnetic tunnel junction; Spin orbits; Stray magnetic fields; Temperature dependence; Working temperatures; Switching
Type
journal article