scholarly journals Spin transport in insulators without exchange stiffness

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Koichi Oyanagi ◽  
Saburo Takahashi ◽  
Ludo J. Cornelissen ◽  
Juan Shan ◽  
Shunsuke Daimon ◽  
...  
Keyword(s):  
Spin Transport ◽  
Spin Diffusion ◽  
Spin Current ◽  
Material Design ◽  
Magnetic Films ◽  
Design Strategies ◽  
Spintronic Devices ◽  
Spin Currents ◽  
New Material ◽  
Conventional Models

Abstract The discovery of new materials that efficiently transmit spin currents has been important for spintronics and material science. The electric insulator Gd3Ga5O12 (GGG), a standard substrate for growing magnetic films, can be a spin current generator, but has never been considered as a superior conduit for spin currents. Here we report spin current propagation in paramagnetic GGG over several microns. Surprisingly, spin transport persists up to temperatures of 100 K $$\gg$$ ≫ Tg = 180 mK, the magnetic glass-like transition temperature of GGG. At 5 K and 3.5 T, we find a spin diffusion length λGGG = 1.8 ± 0.2 μm and a spin conductivity σGGG = (7.3 ± 0.3) × 104 Sm−1 that is larger than that of the record quality magnet Y3Fe5O12 (YIG). We conclude that exchange stiffness is not required for efficient spin transport, which challenges conventional models and provides new material-design strategies for spintronic devices.

Room-temperature spin transport in InAs nanowire lateral spin valve

RSC Advances ◽  
2016 ◽  
Vol 6 (79) ◽  
pp. 75736-75740 ◽  
Author(s):  
Zhicheng Wang ◽  
Dong Pan ◽  
Le Wang ◽  
Tingwen Wang ◽  
Bing Zhao ◽  
...  
Keyword(s):  
Room Temperature ◽  
Spin Transport ◽  
Spin Diffusion ◽  
Diffusion Length ◽  
Spin Valve ◽  
Spintronic Devices ◽  
Spin Diffusion Length ◽  
Nanowire Device ◽  
Large Spin

We report room temperature spin transport in an InAs nanowire device. A large spin signal of 35 kΩ and long spin diffusion length of 1.9 μm are achieved. We believe that these results open a practical way to design InAs NW based spintronic devices.

scholarly journals A new classification method of nanotechnology for design integration in biomaterials

2020 ◽  
Vol 9 (1) ◽  
pp. 820-832 ◽  
Author(s):  
Li Zhang ◽  
Tao Liu ◽  
Yinhong Xie ◽  
Zheng Zeng ◽  
Junying Chen
Keyword(s):  
Artificial Intelligence ◽  
Big Data ◽  
Chemical Reactions ◽  
Material Design ◽  
Classification Method ◽  
Design Strategies ◽  
New Classification ◽  
New Material ◽  
Design Integration ◽  
Design Ideas

AbstractCurrently, advanced biomaterial design solutions often have more than two kinds of nanotechnology design strategies, but there is no suitable classification to describe these designs systematically. Based on the material design ideas and the modes of implementing functions, this article exemplifies and proposes a new nanotechnology classification that includes physical properties, the chemical reactions that respond to the microenvironment and bio-inspired incorporation. If two or more nanotechnology designs in the same classification are to be integrated into the same biological material, it is necessary to analyze the integration conflict between the designs. With the development of big data, this classification method may help researchers and artificial intelligence to realize automated integration of multiple designs and provide new material nanotechnology design integration solutions.

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.

PERFECT ALLOYS FOR SPIN HALL CURRENT-INDUCED MAGNETIZATION SWITCHING

SPIN ◽  
2012 ◽  
Vol 02 (02) ◽  
pp. 1250010 ◽  
Author(s):  
MARTIN GRADHAND ◽  
DMITRY V. FEDOROV ◽  
PETER ZAHN ◽  
INGRID MERTIG ◽  
YOSHICHIKA OTANI ◽  
...  
Keyword(s):  
Hall Effect ◽  
Noble Metals ◽  
Spin Diffusion ◽  
Spin Current ◽  
Material Design ◽  
Spin Hall Effect ◽  
Pure Spin ◽  
Magnetization Switching ◽  
Hall Angle ◽  
Electronic Measurement

We propose a device that allows for magnetization switching in nanomagnets by means of a pure spin current induced by the spin Hall effect. For this purpose we combine the ideas of magnetization switching of a ferromagnet by a spin current produced via the spin accumulation at a ferromagnet/nonmagnet interface with the electronic measurement of the direct spin Hall effect, and the theoretical material design to identify systems with a large spin Hall angle and an appropriate spin diffusion length. We will discuss the device design with respect to the size of the charge and spin currents. Based on ab initio calculations, we predict dilute alloys ideally suited for this application. Noble metals with single-sheeted Fermi surfaces, doped with either heavy impurities like Bi and Pb in Cu or Bi in Ag and light impurities like C and N in Au , seem to be the best candidates for a spin Hall angle larger than 5%.

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 Terahertz Spin Currents and Inverse Spin Hall Effect in Thin-Film Heterostructures Containing Complex Magnetic Compounds

SPIN ◽  
2017 ◽  
Vol 07 (03) ◽  
pp. 1740010 ◽  
Author(s):  
T. Seifert ◽  
U. Martens ◽  
S. Günther ◽  
M. A. W. Schoen ◽  
F. Radu ◽  
...  
Keyword(s):  
Figure Of Merit ◽  
Spin Transport ◽  
Spin Current ◽  
Metallic Multilayers ◽  
Terahertz Emission ◽  
Conduction Electrons ◽  
Spin Currents ◽  
Optical Generation ◽  
Inverse Spin Hall Effect ◽  
Terahertz Emission Spectroscopy

Terahertz emission spectroscopy (TES) of ultrathin multilayers of magnetic and heavy metals has recently attracted much interest. This method not only provides fundamental insights into photoinduced spin transport and spin–orbit interaction at highest frequencies, but has also paved the way for applications such as efficient and ultrabroadband emitters of terahertz (THz) electromagnetic radiation. So far, predominantly standard ferromagnetic materials have been exploited. Here, by introducing a suitable figure of merit, we systematically compare the strength of THz emission from [Formula: see text]/Pt bilayers with [Formula: see text] being a complex ferro-, ferri- and antiferromagnetic metal, that is, dysprosium cobalt (DyCo5), gadolinium iron (Gd[Formula: see text]Fe[Formula: see text]), magnetite (Fe3O4) and iron rhodium (FeRh). We find that the performance in terms of spin-current generation not only depends on the spin polarization of the magnet’s conduction electrons, but also on the specific interface conditions, thereby suggesting TES to be a highly interface-sensitive technique. In general, our results are relevant for all applications that rely on the optical generation of ultrafast spin currents in spintronic metallic multilayers.

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 Anomalous spin Hall and inverse spin Hall effects in magnetic systems

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
X. R. Wang
Keyword(s):  
Hall Effect ◽  
Order Parameter ◽  
Spin Current ◽  
Spin Hall Effect ◽  
Magnetic Systems ◽  
Charge Current ◽  
Spin Currents ◽  
Tensor Quantity ◽  
Hall Effects ◽  
Spin Hall Effects

AbstractSpin current is a very important tensor quantity in spintronics. However, the well-known spin-Hall effect (SHE) can only generate a few of its components whose propagating and polarization directions are perpendicular with each other and to an applied charge current. It is highly desirable in applications to generate spin currents whose polarization can be in any possible direction. Here anomalous SHE and inverse spin-Hall effect (ISHE) in magnetic systems are predicted. Spin currents, whose polarisation and propagation are collinear or orthogonal with each other and along or perpendicular to the charge current, can be generated, depending on whether the applied charge current is along or perpendicular to the order parameter. In anomalous ISHEs, charge currents proportional to the order parameter can be along or perpendicular to the propagating or polarization directions of the spin current.

scholarly journals Quasi-graphitic carbon shell-induced Cu confinement promotes electrocatalytic CO2 reduction toward C2+ products

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Ji-Yong Kim ◽  
Deokgi Hong ◽  
Jae-Chan Lee ◽  
Hyoung Gyun Kim ◽  
Sungwoo Lee ◽  
...  
Keyword(s):  
High Efficiency ◽  
Co2 Reduction ◽  
Value Added ◽  
Material Design ◽  
Catalyst System ◽  
Critical Issue ◽  
Reduction Reaction ◽  
Catalyst Design ◽  
Design Strategies ◽  
Faradaic Efficiency

AbstractFor steady electroconversion to value-added chemical products with high efficiency, electrocatalyst reconstruction during electrochemical reactions is a critical issue in catalyst design strategies. Here, we report a reconstruction-immunized catalyst system in which Cu nanoparticles are protected by a quasi-graphitic C shell. This C shell epitaxially grew on Cu with quasi-graphitic bonding via a gas–solid reaction governed by the CO (g) - CO2 (g) - C (s) equilibrium. The quasi-graphitic C shell-coated Cu was stable during the CO2 reduction reaction and provided a platform for rational material design. C2+ product selectivity could be additionally improved by doping p-block elements. These elements modulated the electronic structure of the Cu surface and its binding properties, which can affect the intermediate binding and CO dimerization barrier. B-modified Cu attained a 68.1% Faradaic efficiency for C2H4 at −0.55 V (vs RHE) and a C2H4 cathodic power conversion efficiency of 44.0%. In the case of N-modified Cu, an improved C2+ selectivity of 82.3% at a partial current density of 329.2 mA/cm2 was acquired. Quasi-graphitic C shells, which enable surface stabilization and inner element doping, can realize stable CO2-to-C2H4 conversion over 180 h and allow practical application of electrocatalysts for renewable energy conversion.

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