scholarly journals Spin-transfer torque in nanoscale magnetic devices

2011 ◽  
Vol 369 (1951) ◽  
pp. 3617-3630 ◽  
Author(s):  
D. C. Ralph ◽  
Y.-T. Cui ◽  
L. Q. Liu ◽  
T. Moriyama ◽  
C. Wang ◽  
...  
Keyword(s):  
New York ◽  
Magnetic Moments ◽  
Critical Currents ◽  
Spin Transfer Torque ◽  
Spin Transfer ◽  
Spin Torque ◽  
Single Shot ◽  
Cornell University ◽  
Magnetic Devices ◽  
Magnetic Switching

We discuss recent highlights from research at Cornell University, Ithaca, New York, regarding the use of spin-transfer torques to control magnetic moments in nanoscale ferromagnetic devices. We highlight progress on reducing the critical currents necessary to produce spin-torque-driven magnetic switching, quantitative measurements of the magnitude and direction of the spin torque in magnetic tunnel junctions, and single-shot measurements of the magnetic dynamics generated during thermally assisted spin-torque switching.

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 Spin-flip scattering engendered quantum spin torque in a Josephson junction

2019 ◽  
Vol 475 (2224) ◽  
pp. 20180775
Author(s):  
Subhajit Pal ◽  
Colin Benjamin
Keyword(s):  
Josephson Junction ◽  
Exchange Coupling ◽  
Magnetic Impurity ◽  
Magnetic Moments ◽  
Quantum Spin ◽  
Spin Transfer Torque ◽  
Spin Transfer ◽  
Spin Torque ◽  
Spin Flip ◽  
Quantum Mechanism

We examine a Josephson junction with two ferromagnets and a magnetic impurity sandwiched between two superconductors. In such ferromagnetic Josephson junctions, equilibrium spin torque exists only when ferromagnets are misaligned. This is explained via the ‘conventional’ mechanism of spin transfer torque, which owes its origin to the misalignment of two ferromagnets. However, we see surprisingly when the magnetic moments of the ferromagnets are aligned parallel or anti-parallel, there is a finite equilibrium spin torque due to the quantum mechanism of spin-flip scattering. We explore the properties of this unique spin-flip scattering-induced equilibrium quantum spin torque, especially its tunability via exchange coupling and phase difference across the superconductors.

scholarly journals Current-induced spin–orbit torques

2011 ◽  
Vol 369 (1948) ◽  
pp. 3175-3197 ◽  
Author(s):  
Pietro Gambardella ◽  
Ioan Mihai Miron
Keyword(s):  
Angular Momentum ◽  
Exchange Coupling ◽  
Spin Transfer Torque ◽  
Spin Transfer ◽  
Spin Torque ◽  
Inversion Symmetry ◽  
Spin Orbit ◽  
Great Flexibility ◽  
Combined Action ◽  
Proper Material

The ability to reverse the magnetization of nanomagnets by current injection has attracted increased attention ever since the spin-transfer torque mechanism was predicted in 1996. In this paper, we review the basic theoretical and experimental arguments supporting a novel current-induced spin torque mechanism taking place in ferromagnetic (FM) materials. This effect, hereafter named spin–orbit (SO) torque, is produced by the flow of an electric current in a crystalline structure lacking inversion symmetry, which transfers orbital angular momentum from the lattice to the spin system owing to the combined action of SO and exchange coupling. SO torques are found to be prominent in both FM metal and semiconducting systems, allowing for great flexibility in adjusting their orientation and magnitude by proper material engineering. Further directions of research in this field are briefly outlined.

scholarly journals Multiple purpose spin transfer torque operated devices

2013 ◽  
Vol 26 (3) ◽  
pp. 227-238
Author(s):  
Thomas Windbacher ◽  
Hiwa Mahmoudi ◽  
Alexander Makarov ◽  
Viktor Sverdlov ◽  
Siegfried Selberherr
Keyword(s):  
Information Processing ◽  
Building Block ◽  
Energy Efficient ◽  
Spin Transfer Torque ◽  
Spin Transfer ◽  
Spin Torque ◽  
Logic Device ◽  
Flip Flop ◽  
Sequential Logic ◽  
Efficient Information

We summarize our recent work on a non-volatile logic building block required for energy-efficient information processing systems. A sequential logic device, in particular, an alternative non-volatile magnetic flip-flop has been introduced. Its properties are investigated and its extension to a very dense shift register is demonstrated. We show that the flip-flop structure inherently exhibits oscillations and discuss its spin torque nano-oscillator properties.

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 A New Circuit Model for Spin-Torque Oscillator Including Perpendicular Torque of Magnetic Tunnel Junction

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Hyein Lim ◽  
Sora Ahn ◽  
Miryeon Kim ◽  
Seungjun Lee ◽  
Hyungsoon Shin
Keyword(s):  
Tunnel Junction ◽  
Giant Magnetoresistance ◽  
New Technology ◽  
Magnetic Tunnel Junction ◽  
Spin Transfer Torque ◽  
Spin Transfer ◽  
Spin Torque ◽  
Mean Oscillation ◽  
Proposed Model ◽  
Level Model

Spin-torque oscillator (STO) is a promising new technology for the future RF oscillators, which is based on the spin-transfer torque (STT) effect in magnetic multilayered nanostructure. It is expected to provide a larger tunability, smaller size, lower power consumption, and higher level of integration than the semiconductor-based oscillators. In our previous work, a circuit-level model of the giant magnetoresistance (GMR) STO was proposed. In this paper, we present a physics-based circuit-level model of the magnetic tunnel junction (MTJ)-based STO. MTJ-STO model includes the effect of perpendicular torque that has been ignored in the GMR-STO model. The variations of three major characteristics, generation frequency, mean oscillation power, and generation linewidth of an MTJ-STO with respect to the amount of perpendicular torque, are investigated, and the results are applied to our model. The operation of the model was verified by HSPICE simulation, and the results show an excellent agreement with the experimental data. The results also prove that a full circuit-level simulation with MJT-STO devices can be made with our proposed model.

scholarly journals Single-shot dynamics of spin–orbit torque and spin transfer torque switching in three-terminal magnetic tunnel junctions

2020 ◽  
Vol 15 (2) ◽  
pp. 111-117 ◽  
Author(s):  
Eva Grimaldi ◽  
Viola Krizakova ◽  
Giacomo Sala ◽  
Farrukh Yasin ◽  
Sébastien Couet ◽  
...  
Keyword(s):  
Tunnel Junctions ◽  
Magnetic Tunnel Junctions ◽  
Spin Transfer Torque ◽  
Spin Transfer ◽  
Single Shot ◽  
Spin Orbit

scholarly journals Magnetic droplet nucleation boundary in orthogonal spin-torque nano-oscillators

2016 ◽  
Vol 7 (1) ◽  
Author(s):  
Sunjae Chung ◽  
Anders Eklund ◽  
Ezio Iacocca ◽  
Seyed Majid Mohseni ◽  
Sohrab R. Sani ◽  
...  
Keyword(s):  
Critical Role ◽  
Perpendicular Magnetic Anisotropy ◽  
Accurate Method ◽  
Spin Transfer Torque ◽  
Spin Transfer ◽  
Spin Torque ◽  
Droplet Nucleation ◽  
Wide Range ◽  
Field Plane

Abstract Static and dynamic magnetic solitons play a critical role in applied nanomagnetism. Magnetic droplets, a type of non-topological dissipative soliton, can be nucleated and sustained in nanocontact spin-torque oscillators with perpendicular magnetic anisotropy free layers. Here, we perform a detailed experimental determination of the full droplet nucleation boundary in the current–field plane for a wide range of nanocontact sizes and demonstrate its excellent agreement with an analytical expression originating from a stability analysis. Our results reconcile recent contradicting reports of the field dependence of the droplet nucleation. Furthermore, our analytical model both highlights the relation between the fixed layer material and the droplet nucleation current magnitude, and provides an accurate method to experimentally determine the spin transfer torque asymmetry of each device.

scholarly journals Lateral spin transfer torque induced magnetic switching at room temperature demonstrated by x-ray microscopy

2013 ◽  
Vol 3 (1) ◽  
Author(s):  
M. Buhl ◽  
A. Erbe ◽  
J. Grebing ◽  
S. Wintz ◽  
J. Raabe ◽  
...  
Keyword(s):  
Room Temperature ◽  
Spin Transfer Torque ◽  
Spin Transfer ◽  
X Ray ◽  
Magnetic Switching
Sign in / Sign up

Export Citation Format

Share Document