Magnetic field-free deterministic switching of a perpendicular magnetic layer by spin-orbit torques

2019 ◽  
Author(s):  
Roberto Orio ◽  
Siegfried Selberherr ◽  
Viktor Sverdlov
Keyword(s):  
Magnetic Field ◽  
Magnetic Layer ◽  
Spin Orbit ◽  
Deterministic Switching

Deterministic Spin–Orbit Torque Switching of a Perpendicularly Polarized Magnet Using Wedge Shape of the Magnet

SPIN ◽  
2016 ◽  
Vol 06 (02) ◽  
pp. 1640008
Author(s):  
Debanjan Bhowmik ◽  
Sayeef Salahuddin
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Data Storage ◽  
Vertical Direction ◽  
Anisotropy Axis ◽  
Spin Orbit ◽  
Micromagnetic Simulations ◽  
Wedge Shape ◽  
Memory Applications ◽  
Deterministic Switching

Spin–orbit torque provides an efficient way to switch magnets for low power memory applications by reducing the current density needed to switch the magnetization. Perpendicularly polarized magnets are preferred for high density data storage applications because of their high thermal stability in scaled dimensions. However, spin–orbit torque cannot switch a perpendicularly polarized magnet deterministically from up to down and down to up in the absence of an external magnetic field because spin–orbit torque alone cannot break the symmetry of the system. This poses a severe challenge to the applicability of spin–orbit torque for memory devices. In this paper, we show through micromagnetic simulations that when spin–orbit torque is applied on a magnet with a wedge shape, the moments of the magnet are aligned in-plane. On removal of the spin–orbit torque the moments deterministically evolve to vertically upward or downward direction because the anisotropy axis of the magnet is tilted away from the vertical direction owing to the wedge shape of the magnet. Thus, spin–orbit torque driven deterministic switching of the magnet in the absence of an external magnetic field is possible.

Spin generation and manipulation based on spin-orbit interaction in semiconductors

2017 ◽  
Author(s):  
J. Nitta
Keyword(s):  
Magnetic Field ◽  
Orbit Interaction ◽  
Degree Of Freedom ◽  
Effective Magnetic Field ◽  
Spin Orbit ◽  
Spin Orbit Interaction ◽  
Spin Degree ◽  
Dimensional Electron Gas ◽  
Spin Orbit Interactions ◽  
Electrical Generation

This chapter focuses on the electron spin degree of freedom in semiconductor spintronics. In particular, the electrostatic control of the spin degree of freedom is an advantageous technology over metal-based spintronics. Spin–orbit interaction (SOI), which gives rise to an effective magnetic field. The essence of SOI is that the moving electrons in an electric field feel an effective magnetic field even without any external magnetic field. Rashba spin–orbit interaction is important since the strength is controlled by the gate voltage on top of the semiconductor’s two-dimensional electron gas. By utilizing the effective magnetic field induced by the SOI, spin generation and manipulation are possible by electrostatic ways. The origin of spin-orbit interactions in semiconductors and the electrical generation and manipulation of spins by electrical means are discussed. Long spin coherence is achieved by special spin helix state where both strengths of Rashba and Dresselhaus SOI are equal.

scholarly journals Reducing Dzyaloshinskii-Moriya interaction and field-free spin-orbit torque switching in synthetic antiferromagnets

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Ruyi Chen ◽  
Qirui Cui ◽  
Liyang Liao ◽  
Yingmei Zhu ◽  
Ruiqi Zhang ◽  
...  
Keyword(s):  
Domain Wall ◽  
Tunnel Junctions ◽  
Low Power Consumption ◽  
Stray Field ◽  
Magnetic Memory ◽  
Spin Orbit ◽  
Theoretic Analysis ◽  
Spintronic Devices ◽  
Deterministic Switching ◽  
Moriya Interaction

AbstractPerpendicularly magnetized synthetic antiferromagnets (SAF), possessing low net magnetization and high thermal stability as well as easy reading and writing characteristics, have been intensively explored to replace the ferromagnetic free layers of magnetic tunnel junctions as the kernel of spintronic devices. So far, utilizing spin-orbit torque (SOT) to realize deterministic switching of perpendicular SAF have been reported while a large external magnetic field is typically needed to break the symmetry, making it impractical for applications. Here, combining theoretic analysis and experimental results, we report that the effective modulation of Dzyaloshinskii-Moriya interaction by the interfacial crystallinity between ferromagnets and adjacent heavy metals plays an important role in domain wall configurations. By adjusting the domain wall configuration between Bloch type and Néel type, we successfully demonstrate the field-free SOT-induced magnetization switching in [Co/Pd]/Ru/[Co/Pd] SAF devices constructed with a simple wedged structure. Our work provides a practical route for utilization of perpendicularly SAF in SOT devices and paves the way for magnetic memory devices with high density, low stray field, and low power consumption.

scholarly journals Controllable field-free switching of perpendicular magnetization through bulk spin-orbit torque in symmetry-broken ferromagnetic films

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Xuejie Xie ◽  
Xiaonan Zhao ◽  
Yanan Dong ◽  
Xianlin Qu ◽  
Kun Zheng ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Domain Walls ◽  
Single Layer ◽  
Ferromagnetic Film ◽  
Effective Field ◽  
Composition Gradient ◽  
Spin Orbit ◽  
Interlayer Exchange Coupling ◽  
Magnetization Switching ◽  
Perpendicular Magnetization

AbstractProgrammable magnetic field-free manipulation of perpendicular magnetization switching is essential for the development of ultralow-power spintronic devices. However, the magnetization in a centrosymmetric single-layer ferromagnetic film cannot be switched directly by passing an electrical current in itself. Here, we demonstrate a repeatable bulk spin-orbit torque (SOT) switching of the perpendicularly magnetized CoPt alloy single-layer films by introducing a composition gradient in the thickness direction to break the inversion symmetry. Experimental results reveal that the bulk SOT-induced effective field on the domain walls leads to the domain walls motion and magnetization switching. Moreover, magnetic field-free perpendicular magnetization switching caused by SOT and its switching polarity (clockwise or counterclockwise) can be reversibly controlled in the IrMn/Co/Ru/CoPt heterojunctions based on the exchange bias and interlayer exchange coupling. This unique composition gradient approach accompanied with electrically controllable SOT magnetization switching provides a promising strategy to access energy-efficient control of memory and logic devices.

Superconductors with spin–orbit interactions

2016 ◽  
Vol 30 (25) ◽  
pp. 1650183 ◽  
Author(s):  
Yu. N. Ovchinnikov
Keyword(s):  
Magnetic Field ◽  
Superconducting Films ◽  
Critical Magnetic Field ◽  
Spin Orbit ◽  
Zero Temperature ◽  
Interband Pairing ◽  
Two Parameters ◽  
Spin Orbit Interactions ◽  
Parameter Values ◽  
Thin Superconducting Films

The effect of spin-orbit (SO) interaction on the formation of the critical states in thin superconducting films in magnetic field oriented along the film is investigated. Hereby, the case of interband pairing is considered. It was found that eight branches exist in the plane of two parameters [Formula: see text] determined by the value of magnetic field and SO interaction. Six modes leads to inhomogeneous states with different values of the impulse [Formula: see text]. Each state is doubly degenerate over direction of impulse [Formula: see text]. The parameter values at critical point are found for all eight branches in explicit form for zero temperature. The optimal two branches are estimated, corresponding to largest critical magnetic field value for given SO interaction.

SPIN-SPLITTING OF THE BOUND POLARON'S GROUND STATE BINDING ENERGY INDUCED BY THE RASHBA SPIN–ORBIT INTERACTION UNDER THE PERPENDICULAR MAGNETIC FIELD

2008 ◽  
Vol 22 (12) ◽  
pp. 1923-1932
Author(s):  
JIA LIU ◽  
ZI-YU CHEN
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Binding Energy ◽  
Ground State ◽  
Spin Splitting ◽  
Perpendicular Magnetic Field ◽  
Spin Orbit ◽  
Ground State Binding Energy ◽  
Bound Polaron ◽  
Rashba Spin

The influence of a perpendicular magnetic field on a bound polaron near the interface of a polar–polar semiconductor with Rashba effect has been investigated. The material is based on a GaAs / Al x Ga 1-x As heterojunction and the Al concentration varying from 0.2 ≤ x ≤ 0.4 is the critical value below which the Al x Ga 1-x As is a direct band gap semiconductor.The external magnetic field strongly altered the ground state binding energy of the polaron and the Rashba spin–orbit (SO) interaction originating from the inversion asymmetry in the heterostructure splitting of the ground state binding energy of the bound polaron. How the ground state binding energy will be with the change of the external magnetic field, the location of a single impurity and the electron area density have been shown in this paper, taking into account the SO coupling. The contribution of the phonons are also considered. It is found that the spin-splitting states of the bound polaron are more stable, and, in the condition of weak magnetic field, the Zeeman effect can be neglected.

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