Materials, Devices and Spin Transfer Torque in Antiferromagnetic Spintronics: A Concise Review

SPIN ◽  
2017 ◽  
Vol 07 (03) ◽  
pp. 1740014 ◽  
Author(s):  
Cormac Ó Coileáin ◽  
Han Chun Wu
Keyword(s):  
Magnetic Fields ◽  
Spin Transfer Torque ◽  
Spin Transfer ◽  
Tetragonal Structure ◽  
Next Generation ◽  
Tunnel Magnetoresistance ◽  
Spintronic Devices ◽  
Concise Review ◽  
Plane Anisotropy ◽  
Magnetic States

From historical obscurity, antiferromagnets are recently enjoying revived interest, as antiferromagnetic (AFM) materials may allow the continued reduction in size of spintronic devices. They have the benefit of being insensitive to parasitic external magnetic fields, while displaying high read/write speeds, and thus poised to become an integral part of the next generation of logical devices and memory. They are currently employed to preserve the magnetoresistive qualities of some ferromagnetic based giant or tunnel magnetoresistance systems. However, the question remains how the magnetic states of an antiferromagnet can be efficiently manipulated and detected. Here, we reflect on AFM materials for their use in spintronics, in particular, newly recognized antiferromagnet Mn2Au with its in-plane anisotropy and tetragonal structure and high Néel temperature. These attributes make it one of the most promising candidates for AFM spintronics thus far with the possibility of architectures freed from the need for ferromagnetic (FM) elements. Here, we discuss its potential for use in ferromagnet-free spintronic devices.

Magnetization switching by magnon-mediated spin torque through an antiferromagnetic insulator

Science ◽  
2019 ◽  
Vol 366 (6469) ◽  
pp. 1125-1128 ◽  
Author(s):  
Yi Wang ◽  
Dapeng Zhu ◽  
Yumeng Yang ◽  
Kyusup Lee ◽  
Rahul Mishra ◽  
...  
Keyword(s):  
Spin Transfer Torque ◽  
Spin Transfer ◽  
Spin Torque ◽  
Local Magnetization ◽  
Magnetization Switching ◽  
Spintronic Devices ◽  
Magnetic Devices ◽  
Alternative Approach ◽  
Efficient Control ◽  
Electrical Spin

Widespread applications of magnetic devices require an efficient means to manipulate the local magnetization. One mechanism is the electrical spin-transfer torque associated with electron-mediated spin currents; however, this suffers from substantial energy dissipation caused by Joule heating. We experimentally demonstrated an alternative approach based on magnon currents and achieved magnon-torque–induced magnetization switching in Bi2Se3/antiferromagnetic insulator NiO/ferromagnet devices at room temperature. The magnon currents carry spin angular momentum efficiently without involving moving electrons through a 25-nanometer-thick NiO layer. The magnon torque is sufficient to control the magnetization, which is comparable with previously observed electrical spin torque ratios. This research, which is relevant to the energy-efficient control of spintronic devices, will invigorate magnon-based memory and logic devices.

scholarly journals Tunnel magnetoresistance and spin transfer torque in magnetic tunnel junction with embedded nanoparticles

2018 ◽  
Vol 185 ◽  
pp. 01015
Author(s):  
Niazbeck Useinov
Keyword(s):  
Ballistic Transport ◽  
Magnetic Tunnel Junction ◽  
Mean Free Path ◽  
Spin Transfer Torque ◽  
Spin Transfer ◽  
Tunnel Magnetoresistance ◽  
Spin Dependent Transport ◽  
Plane Component ◽  
Dependent Transport ◽  
Embedded Nanoparticles

The theoretical model of spin-dependent transport in magnetic tunnel junctions (MTJ) containing magnetic or non-magnetic nanoparticle is developed. The dependences of tunnel magnetoresistance (TMR) and in-plane component of spin transfer torque (STT) on the applied voltage for various sizes of nanoparticles of the order of the mean free path of the conduction electron are calculated. The calculation is performed in the approximation of the ballistic transport of conduction electrons through the insulating layers of the MTJ and the nanoparticles.

Enhancing Frequency and Reducing the Power of Spin-Torque Nanooscillator By The Generated Oersted Field

SPIN ◽  
2020 ◽  
Vol 10 (02) ◽  
pp. 2050012
Author(s):  
H. Bhoomeeswaran ◽  
P. Sabareesan
Keyword(s):  
Spin Valve ◽  
Spin Transfer Torque ◽  
Spin Transfer ◽  
Spin Torque ◽  
Spintronic Devices ◽  
Frequency Tunability ◽  
Spin Polarized ◽  
The Individual ◽  
Promising Source ◽  
Nonmagnetic Spacer

The current-driven magnetization precession dynamics stimulated by Spin-Transfer Torque (STT) in a trilayer spin-valve device (typically Spin-Torque Nanooscillator (STNO)) is numerically investigated by solving the Landau–Lifshitz–Gilbert–Slonczewski (LLGS) equation. We have devised four STNO devices made of ferromagnetic alloys such as CoPt, CoFeB, Fe[Formula: see text]B[Formula: see text]Ni2 and EuO, which act as free and fixed layers. Here, copper acts as a nonmagnetic spacer for all the devices. In this work, we have introduced the current-induced Oersted field, which is generated when a spin-polarized current passes through the device. The generated Oersted field strength is varied by increasing the diameter of the STNO device. Frequency tunability is achieved in all the four devices, whereas the power of the individual device reduces. The frequency and power of the devices depend entirely on the saturation magnetization of the material, which inherently reflects in the current density and the coherence of the spin-polarized DC. In all devices, the frequency increases, whereas the power decreases by increasing the strength of the Oersted field. Among the four devices, the maximum frequency can be tuned up to 104[Formula: see text]GHz with 40[Formula: see text]nm device diameter, which is obtained for EuO material. This opens a promising source and paves a glittering future for the nanoscale spintronic devices.

scholarly journals Theoretical Study of Field-Free Switching in PMA-MTJ Using Combined Injection of STT and SOT Currents

Micromachines ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 1345
Author(s):  
Shaik Wasef ◽  
Hossein Fariborzi
Keyword(s):  
Critical Current ◽  
Theoretical Study ◽  
Tunnel Junctions ◽  
Spin Transfer Torque ◽  
Spin Transfer ◽  
Spin Orbit ◽  
Micromagnetic Simulations ◽  
Spintronic Devices ◽  
Current Densities ◽  
The Relationship

Field-free switching in perpendicular magnetic tunnel junctions (P-MTJs) can be achieved by combined injection of spin-transfer torque (STT) and spin-orbit torque (SOT) currents. In this paper, we derived the relationship between the STT and SOT critical current densities under combined injection. We included the damping–like torque (DLT) and field-like torque (FLT) components of both the STT and SOT. The results were derived when the ratio of the FLT to the DLT component of the SOT was positive. We observed that the relationship between the critical SOT and STT current densities depended on the damping constant and the magnitude of the FLT component of the STT and the SOT current. We also noted that, unlike the FLT component of SOT, the magnitude and sign of the FLT component of STT did not have a significant effect on the STT and SOT current densities required for switching. The derived results agreed well with micromagnetic simulations. The results of this work can serve as a guideline to model and develop spintronic devices using a combined injection of STT and SOT currents.

scholarly journals Micromagnetic Simulation of Spin Transfer Torque Magnetization Precession Phase Diagram in a Spin-Valve Nanopillar under External Magnetic Fields

2012 ◽  
Vol 2012 ◽  
pp. 1-12 ◽  
Author(s):  
H. B. Huang ◽  
X. Q. Ma ◽  
Z. H. Liu ◽  
X. M. Shi ◽  
T. Yue ◽  
...  
Keyword(s):  
Phase Diagram ◽  
Magnetic Fields ◽  
Dynamic Balance ◽  
Spin Valve ◽  
Spin Transfer Torque ◽  
Micromagnetic Simulation ◽  
Spin Transfer ◽  
Magnetization Distribution ◽  
Magnetization Precession ◽  
Evolution Behavior

We investigated spin transfer torque magnetization precession in a nanoscale pillar spin-valve under external magnetic fields using micromagnetic simulation. The phase diagram of the magnetization precession is calculated and categorized into four states according to their characteristics. Of the four states, the precessional state has two different modes: steady precession mode and substeady precession mode. The different modes originate from the dynamic balance between the spin transfer torque and the Gilbert damping torque. Furthermore, we reported the behavior of the temporal evolutions of magnetization components in steady precession mode at the condition of the applied magnetic field using the orbit projection method and explaining perfectly the magnetization components evolution behavior. In addition, a result of a nonuniform magnetization distribution is observed in the free layer due to the excitation of non-uniform mode.

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