scholarly journals Seebeck Effect in Nanomagnets

2021 ◽  
Author(s):  
Dmitry Fedorov ◽  
Martin Gradhand ◽  
Katarina Tauber ◽  
Gerrit E. W. Bauer ◽  
Ingrid Mertig
Keyword(s):  
Temperature Gradient ◽  
Spin Diffusion ◽  
Diffusion Length ◽  
Seebeck Effect ◽  
Spin Accumulation ◽  
Heat Accumulation ◽  
Ettingshausen Effect ◽  
Transverse Temperature ◽  
Dilute Magnetic Alloys ◽  
Spin Heat Accumulation

Abstract We present a theory of the Seebeck effect in nanomagnets with dimensions smaller than the spin diffusion length, showing that the spin accumulation generated by a temperature gradient strongly affects the thermopower. We also identify a correction arising from the transverse temperature gradient induced by the anomalous Ettingshausen effect and an induced spin-heat accumulation gradient. The relevance of these effects for nanoscale magnets is illustrated by ab initio calculations on dilute magnetic alloys.on dilute magnetic alloys.

Manipulating Spin Current in the Magnetic Nanopillar

2007 ◽  
Vol 7 (1) ◽  
pp. 259-264 ◽  
Author(s):  
T. Yang ◽  
A. Hirohata ◽  
T. Kimura ◽  
Y. Otani
Keyword(s):  
Layer Thickness ◽  
Spin Relaxation ◽  
Spin Diffusion ◽  
Diffusion Length ◽  
Ferromagnetic Layer ◽  
Spin Current ◽  
Spin Accumulation ◽  
Magnetization Switching ◽  
Capping Layer ◽  
Spin Diffusion Length

Because of the capability to switch the magnetization of a nanoscale magnet, the spin transfer effect is critical for the application of magnetic random access memory. For this purpose, it is important to enhance the spin current carried by the charge current. Calculations based on the diffusive spin-dependent transport equations reveal that the magnitude of spin current can be tuned by modifying the ferromagnetic layer and the spin relaxation process in the device. Increasing the ferromagnetic layer thickness is found to enhance both the spin current and the spin accumulation. On the other hand, a strong spin relaxation in the capping layer also increases the spin current but suppresses the spin accumulation. To demonstrate the theoretical results, nanopillar structures with the size of ∼100 nm are fabricated and the current-induced magnetization switching behaviors are experimentally studied. When the ferromagnetic layer thickness is increased from 3 nm to 20 nm, the critical switching current for the current-induced magnetization switching is significantly reduced, indicating the enhancement of the spin current. When the Au capping layer with a short spin-diffusion length replaces the Cu capping layer with a long spin-diffusion length, the reduction of the critical switching current is also observed.

scholarly journals Enhanced Spin Accumulation in Semiconductor at Room Temperature Using Ni0.65Zn0.35Fe2O4(NZFO) as Spin Injector in NZFO/MgO/p-Si Device

2021 ◽  
Vol 8 ◽  
Author(s):  
Nilay Maji ◽  
Subhasis Shit ◽  
T. K. Nath
Keyword(s):  
Room Temperature ◽  
Spin Diffusion ◽  
Diffusion Length ◽  
Spin Injection ◽  
Spin Accumulation ◽  
Injection Model ◽  
Tunnel Contact ◽  
Current Voltage ◽  
Spin Polarized ◽  
Junction Structure

In this article, the fabrication of a Ni0.65Zn0.35Fe2O4/MgO/p-Si heterostructure device has been optimized using the pulsed laser deposition (PLD) technique, and a detailed investigation of its structural, electrical, and magnetic features has been performed experimentally. The electronic and magneto-transport characteristics have been explored in the temperature range of 100–300 K. The current-voltage (I-V) characteristics of the heterojunction have been recorded, which displayed an excellent rectifying magnetic tunnel diode-like behavior throughout that temperature regime. The application of an external magnetic field parallel to the plane of the NZFO film causes the current (I) across the junction to decrease, clearly indicating positive junction magnetoresistance (JMR) of the heterostructure. The root of displaying positive magnetoresistance in our heterojunction has been well justified using the standard spin injection model. The electrical injection of spin-polarized carriers and its accumulation and detection in a p-Si channel have been demonstrated using the NZFO/MgO tunnel contact using a three-terminal (3-T) Hanle device. The parameters such as spin lifetime (99 ps), spin diffusion length (276 nm), and spin polarization (0.44) have been estimated from the Hanle curve detected in our heterostructure at room temperature, making the Ni0.65Zn0.35Fe2O4/MgO/p-Si device a very favorable promising junction structure in the field of spintronics for several device appliances in the future.

Large Spin Accumulation with Long Spin Diffusion Length in Cu/MgO/Permalloy Lateral Spin Valves

2011 ◽  
Vol 4 (6) ◽  
pp. 063002 ◽  
Author(s):  
Taro Wakamura ◽  
Kohei Ohnishi ◽  
Yasuhiro Niimi ◽  
YoshiChika Otani
Keyword(s):  
Spin Diffusion ◽  
Diffusion Length ◽  
Spin Valves ◽  
Spin Accumulation ◽  
Spin Diffusion Length ◽  
Large Spin

scholarly journals Spin Seebeck Effect in a Hybridized Quantum-Dot/Majorana-Nanowire With Spin Heat Accumulation

2021 ◽  
Vol 9 ◽  
Author(s):  
Lian-Liang Sun ◽  
Zhen-Guo Fu
Keyword(s):  
Quantum Dot ◽  
Spin Polarization ◽  
High Efficiency ◽  
Seebeck Effect ◽  
Heat Accumulation ◽  
Topological Superconductor ◽  
Semiconductor Nanowire ◽  
Spin Seebeck Effect ◽  
Spin Polarized ◽  
Spin Heat Accumulation

Properties of spin Seebeck effect (SSE) in a quantum dot (QD) connected to a topological superconductor or semiconductor nanowire with strong spin-orbit interaction are theoretically studied by the noneqilibrium Green’s function method combined with Dyson equation technique. At low temperatures, Majorana zero modes (MZMs) are prepared at the ends of topological superconductor or semiconductor nanowire, and are hybridized to the QD with spin-dependent strength. We consider that the QD is coupled to two leads in the presence of spin heat accumulation (SHA), i.e., spin-dependent temperature in the leads. We find that the thermopower is spin-polarized when the hybridization strength between the QD and one mode of the MZMs depends on electron spin direction, and its spin-polarization can be effectively adjusted by changing the magnitude of SHA. By proper variation of the spin-polarization of the QD-MZM hybridization strength, magnitude of the SHA, dot level, or the direct coupling between the MZMs, 100% spin-polarized or pure thermopower can be generated. Our results may find real usage in high efficiency spintronic devices or detection of the MZMs, which are under current extensive study. The present model is within the reach of current nano-technologies and may by used in high efficiency spin caloritronics devices.

Experimental estimation of the spin diffusion length in undoped p-Ge on Fe3Si using vertical spin-valve devices

2021 ◽  
Vol 129 (1) ◽  
pp. 013901
Author(s):  
A. Yamada ◽  
M. Yamada ◽  
T. Shiihara ◽  
M. Ikawa ◽  
S. Yamada ◽  
...  
Keyword(s):  
Spin Diffusion ◽  
Diffusion Length ◽  
Spin Valve ◽  
Experimental Estimation ◽  
Spin Diffusion Length

scholarly journals Self-consistent determination of spin Hall angle and spin diffusion length in Pt and Pd: The role of the interface spin loss

2018 ◽  
Vol 4 (6) ◽  
pp. eaat1670 ◽  
Author(s):  
Xinde Tao ◽  
Qi Liu ◽  
Bingfeng Miao ◽  
Rui Yu ◽  
Zheng Feng ◽  
...  
Keyword(s):  
Spin Diffusion ◽  
Diffusion Length ◽  
Self Consistent ◽  
Hall Angle ◽  
Spin Diffusion Length

scholarly journals Experimental Study of the Temperature Distribution in CRTS-II Ballastless Tracks on a High-Speed Railway Bridge

2020 ◽  
Vol 10 (6) ◽  
pp. 1980 ◽  
Author(s):  
Lei Zhao ◽  
Ling-Yu Zhou ◽  
Guang-Chao Zhang ◽  
Tian-Yu Wei ◽  
Akim D. Mahunon ◽  
...  
Keyword(s):  
High Temperature ◽  
Temperature Distribution ◽  
Temperature Gradient ◽  
High Speed ◽  
Railway Track ◽  
Vertical Temperature ◽  
High Speed Railway ◽  
Extreme High Temperature ◽  
Transverse Temperature ◽  
Temperature Test

To study the temperature distribution in the China Railway Track System Type II ballastless slab track on a high-speed railway (HSR) bridge, a 1:4 scaled specimen of a simply-supported concrete box girder bridge with a ballastless track was constructed in laboratory. Through a rapid, extreme high temperature test in winter and a conventional high temperature test in summer, the temperature distribution laws in the track on the HSR bridge were studied, and the vertical and transverse temperature distribution trend was suggested for the track. Firstly, the extreme high temperature test results showed that the vertical temperature and the vertical temperature difference distribution in the track on HSR bridge were all nonlinear with three stages. Secondly, the extreme high temperature test showed that the transverse temperature distribution in the track was of quadratic parabolic nonlinear form, and the transverse temperature gradient in the bottom base was significantly higher than that of the other layers of the track. Thirdly, the three-dimensional temperature distribution in the track on HSR bridge was a nonlinear, three-stage surface. Furthermore, similar regularities were also obtained in the conventional high temperature test, in which the temperature span ranges were different from those of the extreme high temperature test. In addition, the conventional high temperature test also showed that under the natural environment conditions, the internal temperature gradient in the track layers changed periodically (over a period of 24 h).

scholarly journals Long Spin Diffusion Length in Few-Layer Graphene Flakes

2016 ◽  
Vol 117 (14) ◽  
Author(s):  
W. Yan ◽  
L. C. Phillips ◽  
M. Barbone ◽  
S. J. Hämäläinen ◽  
A. Lombardo ◽  
...  
Keyword(s):  
Spin Diffusion ◽  
Diffusion Length ◽  
Layer Graphene ◽  
Graphene Flakes ◽  
Spin Diffusion Length ◽  
Few Layer Graphene
Sign in / Sign up

Export Citation Format

Share Document