On the origin of decay of spin current with temperature in organic spintronic devices

2012 ◽  
Vol 13 (11) ◽  
pp. 2653-2658 ◽  
Author(s):  
Sayani Majumdar ◽  
Himadri S. Majumdar
Keyword(s):  
Spin Current ◽  
Spintronic Devices

scholarly journals Evidence for spin current driven Bose-Einstein condensation of magnons

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
B. Divinskiy ◽  
H. Merbouche ◽  
V. E. Demidov ◽  
K. O. Nikolaev ◽  
L. Soumah ◽  
...  
Keyword(s):  
Room Temperature ◽  
Chemical Potential ◽  
Spin Current ◽  
Einstein Condensation ◽  
Electronic Control ◽  
Spintronic Devices ◽  
Bose Einstein Condensation ◽  
Magnetic Insulators ◽  
Spatially Extended ◽  
Bose Einstein

AbstractThe quanta of magnetic excitations – magnons – are known for their unique ability to undergo Bose-Einstein condensation at room temperature. This fascinating phenomenon reveals itself as a spontaneous formation of a coherent state under the influence of incoherent stimuli. Spin currents have been predicted to offer electronic control of Bose-Einstein condensates, but this phenomenon has not been experimentally evidenced up to now. Here we show that current-driven Bose-Einstein condensation can be achieved in nanometer-thick films of magnetic insulators with tailored nonlinearities and minimized magnon interactions. We demonstrate that, above a certain threshold, magnons injected by the spin current overpopulate the lowest-energy level forming a highly coherent spatially extended state. We quantify the chemical potential of the driven magnon gas and show that, at the critical current, it reaches the energy of the lowest magnon level. Our results pave the way for implementation of integrated microscopic quantum magnonic and spintronic devices.

Spin-Current Modulation in Hexagonal Buckled ZnTe and CdTe Monolayers for Self-Powered Flexible-Piezo-Spintronic Devices

2021 ◽  
Vol 13 (34) ◽  
pp. 40872-40879
Author(s):  
Manish Kumar Mohanta ◽  
Fathima IS ◽  
Amal Kishore ◽  
Abir De Sarkar
Keyword(s):  
Spin Current ◽  
Current Modulation ◽  
Spintronic Devices ◽  
Self Powered

scholarly journals Spin-dependent transport and functional design in organic ferromagnetic devices

2017 ◽  
Vol 8 ◽  
pp. 1919-1931 ◽  
Author(s):  
Guichao Hu ◽  
Shijie Xie ◽  
Chuankui Wang ◽  
Carsten Timm
Keyword(s):  
High Performance ◽  
Spin Current ◽  
Spin Correlation ◽  
Functional Design ◽  
Strong Electron ◽  
Spintronic Devices ◽  
Spin Dependent Transport ◽  
Organic Ferromagnets ◽  
Dependent Transport ◽  
Orbital Analysis

Organic ferromagnets are intriguing materials in that they combine ferromagnetic and organic properties. Although challenges in their synthesis still remain, the development of organic spintronics has triggered strong interest in high-performance organic ferromagnetic devices. This review first introduces our theory for spin-dependent electron transport through organic ferromagnetic devices, which combines an extended Su–Schrieffer–Heeger model with the Green’s function method. The effects of the intrinsic interactions in the organic ferromagnets, including strong electron–lattice interaction and spin–spin correlation between π-electrons and radicals, are highlighted. Several interesting functional designs of organic ferromagnetic devices are discussed, specifically the concepts of a spin filter, multi-state magnetoresistance, and spin-current rectification. The mechanism of each phenomenon is explained by transmission and orbital analysis. These works show that organic ferromagnets are promising components for spintronic devices that deserve to be designed and examined in future experiments.

SPIN CURRENT AMPLIFICATION IN PRESENCE OF NONUNIFORM DOPING

2012 ◽  
Vol 26 (04) ◽  
pp. 1150026
Author(s):  
SH. MIRZAEE ◽  
H. RAHIMPOUR SOLEIMANI
Keyword(s):  
Spin Polarization ◽  
Continuity Equation ◽  
Spin Current ◽  
Polarization Current ◽  
Spintronic Devices ◽  
The Poisson Equation ◽  
Polarization Density ◽  
Amplifying Effect ◽  
Current Amplification ◽  
First Time

In this paper, for the first time in our knowledge, the influence of nonuniform and continuous doping in semiconductor on amplification of spin polarization current especially in n-type GaAs semiconductor have been studied. Numerical calculations based on a selfconsistent solution of the continuity equation, the Poisson equation and rate-equation are used to explain the amplification of spin polarization density. The influences of the diffusion coefficient (Dn) and relaxation time (τsf) on the spin polarization density are also studied. The amplifying effect of nonuniform doping on spin polarization density is important because it might have many applications in spintronic devices.

scholarly journals Spin Current Switching and Spin-Filtering Effects in Mn-Doped Boron Nitride Nanoribbons

2012 ◽  
Vol 2012 ◽  
pp. 1-5 ◽  
Author(s):  
G. A. Nemnes
Keyword(s):  
Boron Nitride ◽  
Spin Current ◽  
Building Blocks ◽  
Magnetic Impurities ◽  
First Principle ◽  
Spin Filter ◽  
Spintronic Devices ◽  
Current Switch ◽  
Boron Nitride Nanoribbons ◽  
Mn Doped

The spin transport properties are investigated by means of the first principle approach for boron nitride nanoribbons with one or two substitutional Mn impurities, connected to graphene electrodes. The spin current polarization is evaluated using the nonequilibrium Green’s function formalism for each structure and bias. The structure with one Mn impurity reveals a transfer characteristics suitable for a spin current switch. In the case of two Mn impurities, the system behaves as an efficient spin-filter device, independent on the ferromagnetic or antiferromagnetic configurations of the magnetic impurities. The experimental availability of the building blocks as well as the magnitudes of the obtained spin current polarizations indicates a strong potential of the analyzed structures for future spintronic devices.

scholarly journals Spin–orbit torque engineering in β-W/CoFeB heterostructures with W–Ta or W–V alloy layers between β-W and CoFeB

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Gyu Won Kim ◽  
Do Duc Cuong ◽  
Yong Jin Kim ◽  
In Ho Cha ◽  
Taehyun Kim ◽  
...  
Keyword(s):  
Metal Layer ◽  
Spin Current ◽  
Hall Conductivity ◽  
Spin Orbit ◽  
Semiconductor Processing ◽  
Spintronic Devices ◽  
New Material ◽  
Switching Efficiency ◽  
Structure Calculations ◽  
Spin Hall Conductivity

AbstractThe spin–orbit torque (SOT) resulting from a spin current generated in a nonmagnetic transition metal layer offers a promising magnetization switching mechanism for spintronic devices. To fully exploit this mechanism, in practice, materials with high SOT efficiencies are indispensable. Moreover, new materials need to be compatible with semiconductor processing. This study introduces W–Ta and W–V alloy layers between nonmagnetic β-W and ferromagnetic CoFeB layers in β-W/CoFeB/MgO/Ta heterostructures. We carry out first-principles band structure calculations for W–Ta and W–V alloy structures to estimate the spin Hall conductivity. While the predicted spin Hall conductivity values of W–Ta alloys decrease monotonically from −0.82 × 103 S/cm for W100 at% as the Ta concentration increases, those of W–V alloys increase to −1.98 × 103 S/cm for W75V25 at% and then gradually decrease. Subsequently, we measure the spin Hall conductivities of both alloys. Experimentally, when β-W is alloyed with 20 at% V, the absolute value of the spin Hall conductivity considerably increases by 36% compared to that of the pristine β-W. We confirm that the W–V alloy also improves the SOT switching efficiency by approximately 40% compared to that of pristine β-W. This study demonstrates a new material that can act as a spin current-generating layer, leading to energy-efficient spintronic devices.

scholarly journals Magnetization switching of a perpendicular nanomagnet induced by vertical nonlocal injection of pure spin current

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Hirofumi Suto ◽  
Tazumi Nagasawa ◽  
Taro Kanao ◽  
Kenichiro Yamada ◽  
Koichi Mizushima
Keyword(s):  
Spin Injection ◽  
Spin Current ◽  
Pure Spin ◽  
Spin Torque ◽  
Device Structure ◽  
Magnetization Switching ◽  
Spintronic Devices ◽  
Perpendicular Magnetization ◽  
Vertical Injection ◽  
Current Flows

AbstractInjection of pure spin current using a nonlocal geometry is a promising method for controlling magnetization in spintronic devices from the viewpoints of increasing freedom in device structure and avoiding problems related to charge current. Here, we report an experimental demonstration of magnetization switching of a perpendicular magnetic nanodot induced by vertical injection of pure spin current from a spin polarizer with perpendicular magnetization. In comparison with direct spin injection, the current amplitude required for magnetization switching is of the same order and shows smaller asymmetry between parallel-to-antiparallel and antiparallel-to-parallel switching. Simulation of spin accumulation reveals that, in the case of nonlocal spin injection, the spin torque is symmetric between the parallel and antiparallel configuration because current flows through only the spin polarizer, not the magnetic nanodot. This characteristic of nonlocal spin injection is the origin of the smaller asymmetry of the switching current and can be advantageous in spintronic applications.

scholarly journals Efficient conversion of orbital Hall current to spin current for spin-orbit torque switching

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Soogil Lee ◽  
Min-Gu Kang ◽  
Dongwook Go ◽  
Dohyoung Kim ◽  
Jun-Ho Kang ◽  
...  
Keyword(s):  
Hall Effect ◽  
Spin Current ◽  
Orbit Coupling ◽  
Recent Theory ◽  
Spin Torque ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Spintronic Devices ◽  
Electric Generation ◽  
Switching Efficiency

AbstractSpin Hall effect, an electric generation of spin current, allows for efficient control of magnetization. Recent theory revealed that orbital Hall effect creates orbital current, which can be much larger than spin-Hall-induced spin current. However, orbital current cannot directly exert a torque on a ferromagnet, requiring a conversion process from orbital current to spin current. Here, we report two effective methods of the conversion through spin-orbit coupling engineering, which allows us to unambiguously demonstrate orbital-current-induced spin torque, or orbital Hall torque. We find that orbital Hall torque is greatly enhanced by introducing either a rare-earth ferromagnet Gd or a Pt interfacial layer with strong spin-orbit coupling in Cr/ferromagnet structures, indicating that the orbital current generated in Cr is efficiently converted into spin current in the Gd or Pt layer. Our results offer a pathway to utilize the orbital current to further enhance the magnetization switching efficiency in spin-orbit-torque-based spintronic devices.

scholarly journals Spin supercurrent in two-dimensional superconductors with Rashba spin-orbit interaction

2019 ◽  
Vol 2 (1) ◽  
Author(s):  
James Jun He ◽  
Kanta Hiroki ◽  
Keita Hamamoto ◽  
Naoto Nagaosa
Keyword(s):  
Chemical Potential ◽  
Spin Current ◽  
Orbit Interaction ◽  
Spin Orbit ◽  
Two Dimensional ◽  
Spin Orbit Interaction ◽  
Spintronic Devices ◽  
Rashba Spin ◽  
Normal States ◽  
Dilute Limit

Abstract Spin current is a central theme in spintronics, and its generation is a keen issue. The spin-polarized current injection from the ferromagnet, spin battery, and spin Hall effect have been used to generate spin current, but Ohmic currents in the normal state are involved in all of these methods. On the other hand, the spin and spin current manipulation by the supercurrent in superconductors is a promising route for dissipationless spintronics. Here we show theoretically that, in two-dimensional superconductors with Rashba spin-orbit interaction, the generation of dissipationless bulk spin current by charge supercurrent becomes highly efficient, exceeding that in normal states in the dilute limit, i.e. when the chemical potential is close to the band edge, although the spin density becomes small there. This result manifests the possibility of creating new spintronic devices with long-range coherence.

scholarly journals Nearly room temperature ferromagnetism in a magnetic metal-rich van der Waals metal

2020 ◽  
Vol 6 (3) ◽  
pp. eaay8912 ◽  
Author(s):  
Junho Seo ◽  
Duck Young Kim ◽  
Eun Su An ◽  
Kyoo Kim ◽  
Gi-Yeop Kim ◽  
...  
Keyword(s):  
Room Temperature ◽  
Room Temperature Ferromagnetism ◽  
Van Der Waals ◽  
Spin Current ◽  
Perpendicular Magnetic Anisotropy ◽  
Long Distance ◽  
Effective Spin ◽  
Experimental Realization ◽  
Spintronic Devices ◽  
Source Operation

In spintronics, two-dimensional van der Waals crystals constitute a most promising material class for long-distance spin transport or effective spin manipulation at room temperature. To realize all-vdW-material–based spintronic devices, however, vdW materials with itinerant ferromagnetism at room temperature are needed for spin current generation and thereby serve as an effective spin source. We report theoretical design and experimental realization of a iron-based vdW material, Fe4GeTe2, showing a nearly room temperature ferromagnetic order, together with a large magnetization and high conductivity. These properties are well retained even in cleaved crystals down to seven layers, with notable improvement in perpendicular magnetic anisotropy. Our findings highlight Fe4GeTe2 and its nanometer-thick crystals as a promising candidate for spin source operation at nearly room temperature and hold promise to further increase Tc in vdW ferromagnets by theory-guided material discovery.

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