scholarly journals Determination of Cobalt Spin-Diffusion Length in Co/Cu Multilayered Heterojunction Nanocylinders Based on Valet–Fert Model

Nanomaterials ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 218
Author(s):  
Saeko Mizoguchi ◽  
Masamitsu Hayashida ◽  
Takeshi Ohgai

Anodized aluminum oxide (AAO) nanochannels of diameter, D, of ~50 nm and length, L, of ~60 µm (L/D: approx. 1200 in the aspect ratio), were synthesized and applied as an electrode for the electrochemical growth of Co/Cu multilayered heterojunction nanocylinders. We synthesized numerous Co/Cu multilayered nanocylinders by applying a rectangular pulsed potential deposition method. The Co layer thickness, tCo, ranged from ~8 to 27 nm, and it strongly depended on the pulsed-potential condition for Co layers, ECo. The Cu layer thickness, tCu, was kept at less than 4 nm regardless of ECo. We applied an electrochemical in situ contact technique to connect a Co/Cu multilayered nanocylinder with a sputter-deposited Au thin layer. Current perpendicular-to-plane giant magnetoresistance (CPP-GMR) effect reached up to ~23% in a Co/Cu multilayered nanocylinder with ~4760 Co/Cu bilayers (tCu: 4 nm and tCo: 8.6 nm). With a decrease in tCo, (ΔR/Rp)−1 was linearly reduced based on the Valet–Fert equation under the condition of tF > lFsf and tN < lNsf. The cobalt spin-diffusion length, lCosf, was estimated to be ~12.5 nm.

Nanomaterials ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 5
Author(s):  
Himeyo Kamimura ◽  
Masamitsu Hayashida ◽  
Takeshi Ohgai

Anodized aluminum oxide (AAO) films, which have numerous nanochannels ca. 75 nm in diameter, D and ca. 70 µm in length, L (ca. 933 in aspect ratio, L/D), were used as a template material for growing Co/Cu multilayered nanowire arrays. The multilayered nanowires with alternating Cu layer and Co layers were synthesized by using an electrochemical pulsed-potential deposition technique. The thickness of the Cu layer was adjusted from ca. 2 to 4 nm while that of the Co layer was regulated from ca. 13 to 51 nm by controlling the pulsed potential parameters. To get a Co/Cu multilayered nanowire in an electrochemical in-situ contact with a sputter-deposited Au thin layer, the pulsed potential deposition was continued up to ca. 5000 cycles until the nanowire reached out toward the surface of AAO template. Current-perpendicular-to-plane giant magnetoresistance (CPP-GMR) effect reached up to ca. 23.5% at room temperature in Co/Cu multilayered nanowires with ca. 3500 Co/Cu bilayers (Cu: 1.4 nm and Co: 18.8 nm). When decreasing the thickness of Co layer, the CPP-GMR value increased due to the Valet–Fert model in the long spin diffusion limit.


2007 ◽  
Vol 7 (1) ◽  
pp. 259-264 ◽  
Author(s):  
T. Yang ◽  
A. Hirohata ◽  
T. Kimura ◽  
Y. Otani

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.


2000 ◽  
Vol 284-288 ◽  
pp. 1247-1248 ◽  
Author(s):  
Yoshiaki Hashimoto ◽  
Shingo Katsumoto ◽  
Chizuko Murayama ◽  
Yasuhiro Iye

1999 ◽  
Vol 60 (1) ◽  
pp. 477-484 ◽  
Author(s):  
S. Dubois ◽  
L. Piraux ◽  
J. M. George ◽  
K. Ounadjela ◽  
J. L. Duvail ◽  
...  

2021 ◽  
Vol 129 (1) ◽  
pp. 013901
Author(s):  
A. Yamada ◽  
M. Yamada ◽  
T. Shiihara ◽  
M. Ikawa ◽  
S. Yamada ◽  
...  

2018 ◽  
Vol 4 (6) ◽  
pp. eaat1670 ◽  
Author(s):  
Xinde Tao ◽  
Qi Liu ◽  
Bingfeng Miao ◽  
Rui Yu ◽  
Zheng Feng ◽  
...  

2016 ◽  
Vol 117 (14) ◽  
Author(s):  
W. Yan ◽  
L. C. Phillips ◽  
M. Barbone ◽  
S. J. Hämäläinen ◽  
A. Lombardo ◽  
...  

2012 ◽  
Vol 508 ◽  
pp. 266-270 ◽  
Author(s):  
K. Harii ◽  
Z. Qiu ◽  
T. Iwashita ◽  
Y. Kajiwara ◽  
K. Uchida ◽  
...  

A Spin Current Generated by Spin Pumping in a Ferromagnetic/Nonmagnetic/Spin-Sink Trilayer Film Is Calculated Based on the Spin Pumping Theory and the Standard Spin Diffusion Equation. By Attaching the Spin-Sink Layer, the Injected Spin Current Is Drastically Enhanced when the Interlayer Thickness Is Shorter than the Spin Diffusion Length of the Interlayer. We Also Provided the Formula of the Charge Current which Is Induced from the Pumped Spin Current via the Inverse Spin-Hall Effect.


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