scholarly journals Unified quaternionic description of charge and spin transport and intrinsic nonlinearity of spin currents

2018 ◽  
Vol 32 (26) ◽  
pp. 1850292
Author(s):  
T. P. Pareek
Keyword(s):  
Spin Transport ◽  
Scattering Matrix ◽  
Unitarity Condition ◽  
Unified Theory ◽  
Current Conservation ◽  
Spin Currents ◽  
Intrinsic Nonlinearity ◽  
Charge Flux ◽  
Vector Part ◽  
Flux Conservation

We present a unified theory of charge and spin transport using quaternionic formalism. It is shown that both charge and spin currents can be combined together to form a quaternionic current. The scalar and vector part of quaternionic currents correspond to charge and spin currents, respectively. We formulate a unitarity condition on the scattering matrix for quaternionic current conservation. It is shown that in the presence of spin flip interactions, a weaker quaternionic unitarity condition implying charge flux conservation but spin flux nonconservation is valid. Using this unified theory, we find that spin currents are intrinsically nonlinear. Its implication for recent experimental observation of spin generation far away from the boundaries are discussed.

SPIN TRANSPORT FOR A QUANTUM WIRE WITH WEAK DRESSELHAUS SPIN-ORBIT COUPLING

2011 ◽  
Vol 25 (07) ◽  
pp. 487-496
Author(s):  
XI FU ◽  
ZESHUN CHEN ◽  
FENG ZHONG ◽  
YONGHONG KONG
Keyword(s):  
Spin Polarization ◽  
Quantum Wire ◽  
Spin Transport ◽  
Scattering Matrix ◽  
Orbit Coupling ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Wall Potential ◽  
Electron Transport Properties ◽  
Scattering Matrix Method

We investigate theoretically the electron transport properties of a quantum wire (QW) non-adiabatically connected to two normal leads with weak Dresselhaus spin-orbit coupling (DSOC). Using the scattering matrix method and Landauer–Büttiker formula within the effective free-electron approximation, we have calculated the spin-dependent conductances G↑/↓ and spin polarization Pz of a hard-wall potential confined QW. It is demonstrated that regardless of the existence of DSOC G↑/↓ and Pz present oscillation structures near the subband edges of QW, and the number of quantized conductance plateaus is determined by the number of propagation modes in two leads. Moreover, the DSOC induces splitting of spin-up and spin-down conductance plateaus as well as the existence of spin polarization (Pz ≠ 0), and the enhancement of Dresselhaus strength destroys the conductance plateaus for the wide QW case. The above results indicate that the spin-dependent conductances and Pz are strongly dependent on the Dresselhaus strength which is the physical basis for spin transistor.

scholarly journals SU(2) × U(1) unified theory for charge, orbit and spin currents

2006 ◽  
Vol 39 (22) ◽  
pp. 7115-7123 ◽  
Author(s):  
Pei-Qing Jin ◽  
You-Quan Li ◽  
Fu-Chun Zhang
Keyword(s):  
Unified Theory ◽  
Spin Currents

Spin Transport and Magneto-Resistance in Organic Semiconductors

2009 ◽  
Vol 1154 ◽  
Author(s):  
Mohammad Yunus ◽  
P. P. Ruden ◽  
Darryl L. Smith
Keyword(s):  
Organic Semiconductors ◽  
Diffusion Approximation ◽  
Carrier Transport ◽  
Spin Transport ◽  
Spin Injection ◽  
Carrier Injection ◽  
Drift Diffusion ◽  
Spin Currents ◽  
Magneto Resistance

AbstractCalculated results for spin injection, transport, and magneto-resistance (MR) in organic semiconductors sandwiched between two ferromagnetic contacts are presented. The carrier transport is modeled by spin dependent device equations in drift-diffusion approximation. In agreement with earlier results, spin injection from ferromagnetic contacts into organic semiconductors can be greatly enhanced if (spin-selective) tunneling is the limiting process for carrier injection. Modeling the tunnel processes with linear contact resistances yields spin currents and MR that tend to increase with increasing bias. We also explore the possibility of bias dependent contact resistances and show that this effect may limit MR to low bias.

SPIN HALL EFFECT

2009 ◽  
Vol 23 (12n13) ◽  
pp. 2556-2565 ◽  
Author(s):  
M. I. DYAKONOV
Keyword(s):  
Hall Effect ◽  
Spin Transport ◽  
Orbit Interaction ◽  
Spin Hall Effect ◽  
Spin Orbit ◽  
Physical Origin ◽  
Spin Orbit Interaction ◽  
Spin Currents ◽  
Spin Dependent Scattering

A review of the phenomenology of the Spin Hall Effect and related phenomena originating from the coupling between spin and charge currents by spin-orbit interaction is presented. The physical origin of various effects in spin-dependent scattering is demonstrated. A previously unknown feature of spin transport, the swapping of spin currents, is discussed.

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.

scholarly journals SU(2)xU(1) unified theory for charge, orbit and spin currents

2006 ◽  
Vol 39 (35) ◽  
pp. 11129-11129 ◽  
Author(s):  
Pei-Qing Jin ◽  
You-Quan Li ◽  
Fu-Chun Zhang
Keyword(s):  
Unified Theory ◽  
Spin Currents

scholarly journals Calculating spin transport properties from first principles: Spin currents

2019 ◽  
Vol 99 (14) ◽  
Author(s):  
R. J. H. Wesselink ◽  
K. Gupta ◽  
Z. Yuan ◽  
Paul J. Kelly
Keyword(s):  
Transport Properties ◽  
First Principles ◽  
Spin Transport ◽  
Spin Currents

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.

“Preparation of Single Crystalline Gold Films for ED Studies”

1972 ◽  
Vol 30 ◽  
pp. 634-635
Author(s):  
Joseph D. C. Peng
Keyword(s):  
Crystal Morphology ◽  
Diffraction Theory ◽  
Scattering Matrix ◽  
Vacuum Evaporation ◽  
Gold Films ◽  
Matrix Formulation ◽  
Silver Films ◽  
Single Crystalline ◽  
Grating Pattern ◽  
Stacking Disorder

The relative intensities of the ED spots in a cross-grating pattern can be calculated using N-beam electron diffraction theory. The scattering matrix formulation of N-beam ED theory has been previously applied to imperfect microcrystals of gold containing stacking disorder (coherent twinning) in the (111) crystal plane. In the present experiment an effort has been made to grow single-crystalline, defect-free (111) gold films of a uniform and accurately know thickness using vacuum evaporation techniques. These represent stringent conditions to be met experimentally; however, if a meaningful comparison is to be made between theory and experiment, these factors must be carefully controlled. It is well-known that crystal morphology, perfection, and orientation each have pronounced effects on relative intensities in single crystals.The double evaporation method first suggested by Pashley was employed with some modifications. Oriented silver films of a thickness of about 1500Å were first grown by vacuum evaporation on freshly cleaved mica, with the substrate temperature at 285° C during evaporation with the deposition rate at 500-800Å/sec.

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