Incoherent spin current

2017 ◽  
Author(s):  
K. Ando ◽  
E. Saitoh
Keyword(s):  
Diffusion Equation ◽  
Spin Density ◽  
Spin Diffusion ◽  
Spin Injection ◽  
Spin Current ◽  
Ferromagnetic Semiconductor ◽  
Electrochemical Potential ◽  
Semiconductor Interface ◽  
Interface Resistance ◽  
Inhomogeneous Spin

This chapter introduces the concept of incoherent spin current. A diffusive spin current can be driven by spatial inhomogeneous spin density. Such spin flow is formulated using the spin diffusion equation with spin-dependent electrochemical potential. The chapter also proposes a solution to the problem known as the conductivity mismatch problem of spin injection into a semiconductor. A way to overcome the problem is by using a ferromagnetic semiconductor as a spin source; another is to insert a spin-dependent interface resistance at a metal–semiconductor interface.

scholarly journals Development of a spin-injection device utilising Gadolinium Nitride

2021 ◽  
Author(s):  
◽  
Kira Pitman
Keyword(s):  
Spin Injection ◽  
Spin Current ◽  
Ferromagnetic Semiconductor ◽  
Experimental Setup ◽  
Injection Device ◽  
Optimal Method ◽  
Multiple Measurement ◽  
Gadolinium Nitride ◽  
Testing Resistance ◽  
Semiconductor Electrodes

<p>In this thesis, the first steps in creating a realisable spin-injection transistor using ferromagnetic semiconductor electrodes are detailed. A spin-injection device utilising the ferromagnetic semiconductor gadolinium nitride has been designed, fabricated and electrically tested. In addition, an experimental setup for future measurements of a spin current in spin-injection devices was adapted to our laboratory-based off one developed by the Shiraishi group at Kyoto University. Issues encountered during fabrication were identified, and an optimal method for fabricating these devices was determined. Gadolinium nitride and copper were used to make the devices on Si/SiO2 substrates.  The electrical integrity and applicability of the devices for future measurements of injected spin-current was determined through electrical device testing. Resistance measurements of electrical pathways within the device were undertaken to determine the successful deposition of the gadolinium nitride and copper. IV measurements to determine if the devices could withstand the current required for spin current measurements were done. The durability of the devices through multiple measurement types was observed. It was determined that although spin-injection devices utilising gadolinium nitride can be successfully fabricated, more work needs to be done to ensure that the electrical pathways through the copper and gadolinium nitride can be consistently reproducible to allow spin-injection measurements to be done.</p>

Spin Pumping in a Ferromagnetic/Nonmagnetic/Spin-Sink Trilayer Film: Spin Current Termination

2012 ◽  
Vol 508 ◽  
pp. 266-270 ◽  
Author(s):  
K. Harii ◽  
Z. Qiu ◽  
T. Iwashita ◽  
Y. Kajiwara ◽  
K. Uchida ◽  
...  
Keyword(s):  
Diffusion Equation ◽  
Hall Effect ◽  
Spin Diffusion ◽  
Diffusion Length ◽  
Spin Current ◽  
Interlayer Thickness ◽  
Spin Pumping ◽  
Charge Current ◽  
Inverse Spin Hall Effect ◽  
Spin Diffusion Length

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.

scholarly journals Development of a spin-injection device utilising Gadolinium Nitride

2021 ◽  
Author(s):  
◽  
Kira Pitman
Keyword(s):  
Spin Injection ◽  
Spin Current ◽  
Ferromagnetic Semiconductor ◽  
Experimental Setup ◽  
Injection Device ◽  
Optimal Method ◽  
Multiple Measurement ◽  
Gadolinium Nitride ◽  
Testing Resistance ◽  
Semiconductor Electrodes

<p>In this thesis, the first steps in creating a realisable spin-injection transistor using ferromagnetic semiconductor electrodes are detailed. A spin-injection device utilising the ferromagnetic semiconductor gadolinium nitride has been designed, fabricated and electrically tested. In addition, an experimental setup for future measurements of a spin current in spin-injection devices was adapted to our laboratory-based off one developed by the Shiraishi group at Kyoto University. Issues encountered during fabrication were identified, and an optimal method for fabricating these devices was determined. Gadolinium nitride and copper were used to make the devices on Si/SiO2 substrates.  The electrical integrity and applicability of the devices for future measurements of injected spin-current was determined through electrical device testing. Resistance measurements of electrical pathways within the device were undertaken to determine the successful deposition of the gadolinium nitride and copper. IV measurements to determine if the devices could withstand the current required for spin current measurements were done. The durability of the devices through multiple measurement types was observed. It was determined that although spin-injection devices utilising gadolinium nitride can be successfully fabricated, more work needs to be done to ensure that the electrical pathways through the copper and gadolinium nitride can be consistently reproducible to allow spin-injection measurements to be done.</p>

Enhanced spin accumulation in nano-pillar-based lateral spin valve using spin reservoir effect

2022 ◽  
Author(s):  
Xiaomin Cui ◽  
Shaojie Hu ◽  
Takashi Kimura
Keyword(s):  
Spin Diffusion ◽  
Spin Injection ◽  
Spin Valve ◽  
Spin Current ◽  
Spin Valves ◽  
Pure Spin ◽  
Spin Accumulation ◽  
Spintronic Devices ◽  
High Bias ◽  
Angle Deposition

Abstract Lateral spin valves are ideal nanostructures for investigating spin-transport physics phenomena and promoting the development of future spintronic devices owing to dissipation-less pure spin current. The magnitude of the spin accumulation signal is well understood as a barometer for characterizing spin current devices. Here, we develop a novel fabrication method for lateral spin valves based on ferromagnetic nanopillar structures using a multi-angle deposition technique. We demonstrate that the spin-accumulation signal is effectively enhanced by reducing the lateral dimension of the nonmagnetic spin channel. The obtained results can be quantitatively explained by the confinement of the spin reservoir by considering spin diffusion into the leads. The temperature dependence of the spin accumulation signal and the influence of the thermal spin injection under a high bias current are also discussed.

scholarly journals Manipulation of spin currents in metallic systems

2011 ◽  
Vol 369 (1948) ◽  
pp. 3136-3149 ◽  
Author(s):  
Yoshichika Otani ◽  
Takashi Kimura
Keyword(s):  
Room Temperature ◽  
Spin Diffusion ◽  
Diffusion Processes ◽  
Spin Injection ◽  
Spin Current ◽  
Hybrid Structures ◽  
Pure Spin ◽  
Spin Currents ◽  
Magnetic Metal ◽  
Hall Effect Measurements

The transport properties of diffusive spin currents have been investigated in lateral ferromagnetic/non-magnetic metal hybrid structures. The spin diffusion processes were found to be strongly dependent on the magnitude of the spin resistances of connected materials. Efficient spin injection and detection are accomplished by optimizing the junction structures on the basis of the spin resistance circuitry. The magnetization switching of a nanoscale ferromagnetic particle and also room temperature spin Hall effect measurements were realized by using an efficient pure-spin-current injection.

scholarly journals Effect of the low-resistance tunnel barriers induced inhomogeneous spin current distribution in graphene crossed configuration lateral spin valve

AIP Advances ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 115005
Author(s):  
Yanping Liu ◽  
Cheng Zeng ◽  
Junnan Ding ◽  
Jiahong Zhong ◽  
Yuanji Gao ◽  
...  
Keyword(s):  
Current Distribution ◽  
Spin Valve ◽  
Spin Current ◽  
Low Resistance ◽  
Tunnel Barriers ◽  
Inhomogeneous Spin

Energy-Efficient Multiferroic Spin-Devices and Spin-Circuits

SPIN ◽  
2020 ◽  
Vol 10 (04) ◽  
pp. 2030001
Author(s):  
Kuntal Roy
Keyword(s):  
Energy Efficient ◽  
Large Scale ◽  
Spin Diffusion ◽  
Diffusion Length ◽  
Spin Current ◽  
Logic Gates ◽  
Low Energy ◽  
Circuit Representation ◽  
Spin Diffusion Length ◽  
Spin Devices

Spin-devices are switched by flipping spins without moving charge in space and this can lead to ultra-low-energy switching replacing traditional transistors in beyond Moore’s law era. In particular, the electric field-induced magnetization switching has emerged to be an energy-efficient paradigm. Here, we review the recent developments on ultra-low-energy, area-efficient, and fast spin-devices using multiferroic magnetoelectric composites. It is shown that both digital logic gates and analog computing with transistor-like high-gain region in the input-output characteristics of multiferroic composites are feasible. We also review the equivalent spin-circuit representation of spin-devices by considering spin potential and spin current similar to the charge-based counterparts using Kirchhoff’s voltage/current laws, which is necessary for the development of large-scale circuits. We review the spin-circuit representation of spin pumping, which happens anyway when there is a material adjacent to a rotating magnetization and therefore it is particularly necessary to be incorporated in device modeling. Such representation is also useful for understanding and proposing experiments. In spin-circuit representation, spin diffusion length is an important parameter and it is shown that a thickness-dependent spin diffusion length reflecting Elliott–Yafet spin relaxation mechanism in platinum is necessary to match the experimental results.

Spin Hall Effect in a Magnetic Field

2001 ◽  
Vol 690 ◽  
Author(s):  
Shufeng Zhang
Keyword(s):  
Magnetic Field ◽  
Diffusion Equation ◽  
Electric Field ◽  
Hall Effect ◽  
Transverse Electric ◽  
Spin Current ◽  
Magnetic Semiconductor ◽  
Hall Voltage ◽  
Spin Polarized ◽  
The Magnetic Field

ABSTRACTWhen a spin-polarized current is injected into a non-magnetic semiconductor, a transverse electric field known as Hall voltage is generated. By using a macroscopic diffusion equation, we derive the Hall voltage in the presence of both spin current and magnetic field. Novel features such as oscillating Hall signals as a function of the magnetic field and geometrical dependence of Hall signals are predicted.

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