Spin and Orbital Hall Effect: Semiclassical Approach

Spintronics is a research field that utilizes the electronic-spin degree of freedom beyond electronics that uses the charge of electrons. Recently, an attempt was made to extend this to include the orbital angular momentum of electrons, and that is called orbitronics or spin-orbitronics. In this article, we review the semiclassical dynamics of a wave packet that describes electrons in solids under slowly varying electromagnetic fields. This will be used to explain the spin or orbital Hall effect, which is a fundamental phenomenon in spin-orbitronics. The presentation given here is simplified and its goal is to provide a warm-up for articles in this issue of Physics and High Technology.

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Optical Spin Hall Effect in Closed Elliptical Plasmonic Nanoslit with Noncircular Symmetry

Nanomaterials ◽

10.3390/nano11040851 ◽

2021 ◽

Vol 11 (4) ◽

pp. 851

Author(s):

Xiaorong Ren ◽

Xiangyu Zeng ◽

Chunxiang Liu ◽

Chuanfu Cheng ◽

Ruirui Zhang ◽

...

Keyword(s):

Angular Momentum ◽

Hall Effect ◽

Light Field ◽

Analytical Calculation ◽

Spin Hall Effect ◽

Spin Component ◽

Phase Gradient ◽

Bright Spots ◽

Principal Axes ◽

Output Field

We investigated the optical spin Hall effect (OSHE) of the light field from a closed elliptical metallic curvilinear nanoslit instead of the usual truncated curvilinear nanoslit. By making use of the characteristic bright spots in the light field formed by the noncircular symmetry of the elliptical slit and by introducing a method to separate the incident spin component (ISC) and converted spin component (CSC) of the output field, the OSHE manifested in the spot shifts in the CSC was more clearly observable and easily measurable. The slope of the elliptical slit, which was inverse along the principal axes, provided a geometric phase gradient to yield the opposite shifts of the characteristic spots in centrosymmetry, with a double shift achieved between the spots. Regarding the mechanism of this phenomenon, the flip of the spin angular momentum (SAM) of CSC gave rise to an extrinsic orbital angular momentum corresponding to the shifts of the wavelet profiles of slit elements in the same rotational direction to satisfy the conservation law. The analytical calculation and simulation of finite-difference time domain were performed for both the slit element and the whole slit ellipse, and the evolutions of the spot shifts as well as the underlying OSHE with the parameters of the ellipse were achieved. Experimental demonstrations were conducted and had consistent results. This study could be of great significance for subjects related to the applications of the OSHE.

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Two Orders of Magnitude Improvement in the Detection Limit of Droplet-Based Micro-Magnetofluidics with Planar Hall Effect Sensors

Engineering Proceedings ◽

10.3390/i3s2021dresden-10105 ◽

2021 ◽

Vol 6 (1) ◽

pp. 47

Author(s):

Julian Schütt ◽

Rico Illing ◽

Oleksii Volkov ◽

Tobias Kosub ◽

Pablo Nicolás Granell ◽

...

Keyword(s):

Detection Limit ◽

Hall Effect ◽

State Of The Art ◽

Limit Of Detection ◽

Research Field ◽

High Throughput Analysis ◽

Planar Hall Effect ◽

Biologically Relevant ◽

Sensing Platform ◽

Order Of Magnitude

The detection, manipulation, and tracking of magnetic nanoparticles is of major importance in the fields of biology, biotechnology, and biomedical applications as labels as well as in drug delivery, (bio-)detection, and tissue engineering. In this regard, the trend goes towards improvements of existing state-of-the-art methodologies in the spirit of timesaving, high-throughput analysis at ultra-low volumes. Here, microfluidics offers vast advantages to address these requirements, as it deals with the control and manipulation of liquids in confined microchannels. This conjunction of microfluidics and magnetism, namely micro-magnetofluidics, is a dynamic research field, which requires novel sensor solutions to boost the detection limit of tiny quantities of magnetized objects. We present a sensing strategy relying on planar Hall effect (PHE) sensors in droplet-based micro-magnetofluidics for the detection of a multiphase liquid flow, i.e., superparamagnetic aqueous droplets in an oil carrier phase. The high resolution of the sensor allows the detection of nanoliter-sized superparamagnetic droplets with a concentration of 0.58 mg cm−3, even when they are only biased in a geomagnetic field. The limit of detection can be boosted another order of magnitude, reaching 0.04 mg cm−³ (1.4 million particles in a single 100 nL droplet) when a magnetic field of 5 mT is applied to bias the droplets. With this performance, our sensing platform outperforms the state-of-the-art solutions in droplet-based micro-magnetofluidics by a factor of 100. This allows us to detect ferrofluid droplets in clinically and biologically relevant concentrations, and even in lower concentrations, without the need of externally applied magnetic fields.

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Research on VR-Based Experiment Space for Complex Electromagnetic Environment

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.403-408.2923 ◽

2011 ◽

Vol 403-408 ◽

pp. 2923-2926 ◽

Cited By ~ 1

Author(s):

Chi Jun Zhang ◽

Wang Sheng Liu

Keyword(s):

Virtual Reality ◽

High Technology ◽

Research Field ◽

Modeling Language ◽

Human Beings ◽

Electromagnetic Environment ◽

Virtual Reality Technology ◽

Virtual Reality Modeling Language

Virtual Reality technology is a hot research field in simulation of complex electromagnetic and its practical environment in the condition of information and high technology war. The paper discussed the main framework of spatial electromagnetic environment computing and simulating, presented realizing method and key arithmetic designing based on Virtual Reality Modeling Language. The work is evidently valuable for quantitative examinations, evaluation, and analysis of complex electromagnetic environment function, diversification, and effect on human beings, electronic units.

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The spin Hall effect of light in moving medium

Modern Physics Letters B ◽

10.1142/s0217984916504273 ◽

2017 ◽

Vol 31 (01) ◽

pp. 1650427 ◽

Cited By ~ 1

Author(s):

Hehe Li ◽

Xinzhong Li ◽

Jingge Wang

Keyword(s):

Angular Momentum ◽

Gravitational Field ◽

Hall Effect ◽

Inhomogeneous Medium ◽

Maxwell's Equations ◽

Potential Method ◽

Spin Hall Effect ◽

Moving Medium ◽

Spin Angular Momentum ◽

Effect Of Light

In this paper, we investigate the spin Hall effect of light in moving inhomogeneous medium using the Gordon metric and the Maxwell’s equations in the gravitational field. Light experiences a moving medium as a gravitational field by means of the Gordon metric. It is shown that the spin Hall effect of light is modified by the motion of medium, and the deflection of the ray trajectory is dependent on the polarization and the motion of the medium. It is interesting that there is no coupling of the spin angular momentum of light and the effective gravitational field when the medium is moving along the direction of the gradient [Formula: see text]. The results provide a potential method for controlling the spin Hall effect of light in medium.

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Phonon Angular Momentum Hall Effect

Nano Letters ◽

10.1021/acs.nanolett.0c03220 ◽

2020 ◽

Vol 20 (10) ◽

pp. 7694-7699

Author(s):

Sungjoon Park ◽

Bohm-Jung Yang

Keyword(s):

Angular Momentum ◽

Hall Effect

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Spin Hall effect of light in inhomogeneous nonlinear medium

Modern Physics Letters B ◽

10.1142/s021798491550270x ◽

2016 ◽

Vol 30 (02) ◽

pp. 1550270

Author(s):

Hehe Li ◽

Xinzhong Li

Keyword(s):

Angular Momentum ◽

Hall Effect ◽

Orbital Angular Momentum ◽

Nonlinear Medium ◽

Spin Hall Effect ◽

Phase Front ◽

Spin Angular Momentum ◽

Linear Complex ◽

Complex Valued ◽

Effect Of Light

In this paper, we investigate the spin Hall effect of a polarized Gaussian beam (GB) in a smoothly inhomogeneous isotropic and nonlinear medium using the method of the eikonal-based complex geometrical optics which describes the phase front and cross-section of a light beam using the quadratic expansion of a complex-valued eikonal. The linear complex-valued eikonal terms are introduced to describe the polarization-dependent transverse shifts of the beam in inhomogeneous nonlinear medium which is called the spin Hall effect of beam. We know that the spin Hall effect of beam is affected by the nonlinearity of medium and include two parts, one originates from the coupling between the spin angular momentum and the extrinsic orbital angular momentum due to the curve trajectory of the center of gravity of the polarized GB and the other from the coupling between the spin angular momentum and the intrinsic orbital angular momentum due to the rotation of the beam with respect to the central ray.

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Transport Properties of Rare Earth Nitrides

10.26686/wgtn.17147666 ◽

2021 ◽

Author(s):

◽

William Holmes-Hewett

Keyword(s):

Angular Momentum ◽

Rare Earth ◽

Hall Effect ◽

Transport Properties ◽

Conduction Band ◽

Anomalous Hall Effect ◽

Optical Measurements ◽

Rare Earth Nitrides ◽

Heavily Doped ◽

Majority Spin

<p>In this thesis we investigate the transport properties of SmN, NdN and GdN, members of the rare earth nitride series of intrinsic ferromagnetic semiconductors. GdN is the central member of the series with seven occupied majority spin 4f states and seven empty minority spin 4f states. Both the filled and unfilled 4f states are some few eV away from the conduction and valence band extrema, resulting in transport properties which are dominated by the extended Gd 5d band. The half filled 4f shell, with zero net orbital angular momentum, furthermore simplifies calculations and as such GdN is the most studied both experimentally and in theory. As one moves to lighter members, the filled 4f states become unfilled states in the conduction band and the 4f shell now has a net orbital angular momentum. Calculations concerning these members are now significantly more complicated, and as such there exists a wide range of predictions concerning the conduction band minima in the lighter rare earth nitrides. To inform the current theoretical and experimental literature we report on three studies concerning the transport properties of SmN, NdN and GdN. To begin we report on the anomalous Hall effect in SmN, NdN and GdN. Under the symmetry of the rock-salt rare earth nitrides the magnitude of the anomalous Hall effect can imply the wave function of the conduction electron (i.e. d or f band). Measurements of the anomalous Hall effect in moderately doped samples are used to show the conduction channel in SmN and NdN is an f band or hybridised f/d band. Furthermore the sign of the anomalous Hall effect can be used to determine the orientation of the spin magnetic moment of the conduction electrons. Optical measurements of SmN, NdN and GdN films are then reported. Optical measurements provide a probe of the band structure of a material via direct transitions between the valence and conduction bands. Measurements of reflectivity and transmission on undoped SmN and NdN films were used to locate the unfilled majority spin 4f bands which form the conduction band minima in each material. Finally a preliminary study of heavily doped SmN, NdN and GdN is discussed. Structural measurements show a reduced lattice parameter while transport results find a significantly enhanced conductivity in heavily doped films. The Curie temperature is found to be enhanced and optical measurements show an increased absorption and red-shifted optical edge in doped films. The superconducting state of SmN is discussed and it is shown only to be present in moderately doped films, i.e. superconductivity is not present in undoped or degenerately doped SmN, within our measurement limits.</p>

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