Suggestion for Direct Observation of Orbital Accumulation

2020 ◽  
Vol 29 (10) ◽  
pp. 22-27
Author(s):  
Sanghoon KIM ◽  
Soon Cheol HONG
Keyword(s):  
Direct Observation ◽  
Precise Measurement ◽  
Magnetic Circular Dichroism ◽  
Measurement Techniques ◽  
High Sensitivity ◽  
Orbital Moment ◽  
Spin Conversion ◽  
Spintronic Devices ◽  
Orbital Magnetic Moment ◽  
Efficient Control

The generation of orbital current is an intriguing research topic not only for developing energy-efficient control of spintronic devices, but also for observing new emerging phenomena, such as orbital-to-spin conversion. During the last two decades, many innovative measurement techniques have been developed for discoveries related to conversions between spin flow and natural phenomena such as light, heat, vibration, and charge flow. Observation of the orbital current also requires efforts that should result in many other state-of-the-art discoveries. However, a direct experimental way to observe the orbital current is still missing. In this article, we suggest that X-ray magnetic circular dichroism (XMCD) measurements may be a good candidate for directly observing the orbital current because it is the only way to detect orbital moment selectively. Just like spin accumulation, orbital current can also accumulate at the edge of a system, giving rise to a non-zero orbital magnetic moment. Although the orbital moment generated by orbital accumulation is expected to have a very small value, ~10‒5 μB, precise measurement with high sensitivity will allow direct observation of the orbital current.

First-Principles Calculation of the Orbital Magnetic Moment of O and Cr in Half-metallic CrO2

2002 ◽  
Vol 718 ◽  
Author(s):  
Horng-Tay Jeng ◽  
G. Y. Guo
Keyword(s):  
Magnetic Moment ◽  
Magnetic Circular Dichroism ◽  
First Principles Calculation ◽  
Orbital Method ◽  
Full Potential ◽  
Local Spin Density Approximation ◽  
Orbital Moment ◽  
Half Metallic ◽  
Orbital Magnetic Moment ◽  
Good Agreement

AbstractThe electronic and magnetic properties of half-metallic CrO2 have been studied by using the full-potential linearized muffin-tin orbital method within the local spin-density approximation (LSDA)+U approach. It is found that the orbital magnetic moment of Cr atom is quenched while O atom exhibit relatively significant orbital moment in CrO2. For the Hubbard U of 3 eV, LSDA+U gives the orbital moment of -0.051μB/atom for Cr and -0.0025μB/atom for O, being in good agreement with the experimental orbital moments of -0.05 for Cr and -0.003μB/atom for O, respectively. In contrast, LSDA gives the orbital moment of -0.037 for Cr and -0.0011 μB/atom for O, being too small as compared with the magnetic circular dichroism measurements. For the larger U considered in this work, both spin and orbital moments almost increase linearly with respect to U.

scholarly journals A Review of Precision Technologies for Optimising Pasture Measurement on Irish Grassland

Agriculture ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 600
Author(s):  
Darren J. Murphy ◽  
Michael D. Murphy ◽  
Bernadette O’Brien ◽  
Michael O’Donovan
Keyword(s):  
Remote Sensing ◽  
Precise Measurement ◽  
Production Systems ◽  
Measurement Techniques ◽  
Grassland Management ◽  
Management Systems ◽  
Sampling Techniques ◽  
Optimal Sampling ◽  
Labour Costs ◽  
Grassland Production

The development of precision grass measurement technologies is of vital importance to securing the future sustainability of pasture-based livestock production systems. There is potential to increase grassland production in a sustainable manner by achieving a more precise measurement of pasture quantity and quality. This review presents an overview of the most recent seminal research pertaining to the development of precision grass measurement technologies. One of the main obstacles to precision grass measurement, sward heterogeneity, is discussed along with optimal sampling techniques to address this issue. The limitations of conventional grass measurement techniques are outlined and alternative new terrestrial, proximal, and remote sensing technologies are presented. The possibilities of automating grass measurement and reducing labour costs are hypothesised and the development of holistic online grassland management systems that may facilitate these goals are further outlined.

scholarly journals Quantitation of Benzodiazepines and Metabolites in Urine by Liquid Chromatography–Tandem Mass Spectrometry

2018 ◽  
Vol 3 (3) ◽  
pp. 397-407
Author(s):  
Yu Zi Zheng ◽  
Dustin R Bunch ◽  
Katherine Lembright ◽  
Sihe Wang
Keyword(s):  
Precise Measurement ◽  
High Sensitivity ◽  
Urine Samples ◽  
Limit Of Quantification ◽  
Internal Standards ◽  
Independent Laboratory ◽  
Chromatography Tandem Mass Spectrometry ◽  
Analytical Recovery ◽  
Liquid Chromatography Tandem Mass ◽  
Analytical Time

Abstract Background Benzodiazepines (BZDs) are central nervous system depressants that are prescribed to prevent seizures, manage anxiety, or help sleep. When misused, BZDs can lead to addiction and sometimes cause death. Measurement of BZDs in urine is used to identify their use, especially in pain management settings. LC-MS/MS is preferred for these measurements because of its high sensitivity and specificity. Here, we report an LC-MS/MS assay for measuring 7 BZDs and metabolites in urine. Methods Urine sample was incubated at 60 °C for 30 min after addition of internal standards and a β-glucuronidase solution. After centrifugation, the supernatant was diluted with methanol and water before being injected onto a C18 analytical column in an LC-MS/MS system for quantification. The analytical time between injections was 4.35 min. The analytes included 7-aminoclonazepam, α-hydroxyalprazolam, α-hydroxytriazolam, oxazepam, lorazepam, nordiazepam, and temazepam. Results The lower limit of quantification ranged from 30 ng/mL to 50 ng/mL with an analytical recovery >80% for all 7 analytes. Total CV was <10% for all analytes (3 concentration levels of 100, 2500, and 5000 ng/mL; n = 30 each). This method had 100% agreement with a GC-MS method offered by an independent laboratory for negative urine samples. For the positive urine samples, this method showed a strong correlation (R > 0.96) with the GC-MS method. Conclusions The LC-MS/MS assay allows accurate and precise measurement of 7 BZDs and metabolites in a single analytical run with a short analytical run time and broad measuring ranges.

Magnetization switching by magnon-mediated spin torque through an antiferromagnetic insulator

Science ◽  
2019 ◽  
Vol 366 (6469) ◽  
pp. 1125-1128 ◽  
Author(s):  
Yi Wang ◽  
Dapeng Zhu ◽  
Yumeng Yang ◽  
Kyusup Lee ◽  
Rahul Mishra ◽  
...  
Keyword(s):  
Spin Transfer Torque ◽  
Spin Transfer ◽  
Spin Torque ◽  
Local Magnetization ◽  
Magnetization Switching ◽  
Spintronic Devices ◽  
Magnetic Devices ◽  
Alternative Approach ◽  
Efficient Control ◽  
Electrical Spin

Widespread applications of magnetic devices require an efficient means to manipulate the local magnetization. One mechanism is the electrical spin-transfer torque associated with electron-mediated spin currents; however, this suffers from substantial energy dissipation caused by Joule heating. We experimentally demonstrated an alternative approach based on magnon currents and achieved magnon-torque–induced magnetization switching in Bi2Se3/antiferromagnetic insulator NiO/ferromagnet devices at room temperature. The magnon currents carry spin angular momentum efficiently without involving moving electrons through a 25-nanometer-thick NiO layer. The magnon torque is sufficient to control the magnetization, which is comparable with previously observed electrical spin torque ratios. This research, which is relevant to the energy-efficient control of spintronic devices, will invigorate magnon-based memory and logic devices.

Assessing and Extending Track Quality Index for Novel Measurement Techniques in Railway Systems

2020 ◽  
Vol 2674 (8) ◽  
pp. 24-36
Author(s):  
Tzu-Hao Yan ◽  
Francesco Corman
Keyword(s):  
Quality Index ◽  
Measurement Techniques ◽  
High Sensitivity ◽  
Single Type ◽  
Railway Systems ◽  
The Status ◽  
Sensitivity Data ◽  
Maintenance Process ◽  
Track Status ◽  
Track Quality

A systematic maintenance process is essential to keeping railway systems safe and reliable. However, performing such maintenance is costly and often results in system disruption. There is a tradeoff between system safety and budgetary constraints; understanding the condition of the track infrastructure is essential to find the balance between needs and costs for decisions about when to perform maintenance. In this study, the track quality index (TQI), which is commonly used to evaluate the status of tracks and to decide maintenance interventions, is reviewed, including 12 TQIs for superstructure and six for substructure. A literature review indicates that TQIs for sleepers and subgrade have not yet been developed. The differences between TQIs are compared using a set of hypothetical raw data. Their capabilities for identifying track irregularities are also investigated based on the EN 13848 regulations. To classify TQI characteristics in a systematic way, this study proposes four concepts: accuracy, sensitivity, data required, and specificity. Accuracy indicates a TQI’s capability of detecting defects; sensitivity indicates how TQIs change according to variations in the defects; specificity relates to the amount of parameters considered, and the ability to pinpoint root causes or global consequences of defects. The results suggest a tradeoff between the four concepts, where high sensitivity can increase the ability to detect the smallest defects but may be affected by bias; more parameters considered may indicate low accuracy when detecting a single type of defect. Therefore, this study suggests railway regulators use multiple TQIs with complementary characteristics for classifying track status.

Characterization of Anisotropic and Irregularly-Shaped Materials by High-Sensitive Thermal Conductivity Measurements

2007 ◽  
Vol 124-126 ◽  
pp. 1641-1644 ◽  
Author(s):  
M. Gustavsson ◽  
Hideaki Nagai ◽  
Takeshi Okutani
Keyword(s):  
Thermal Conductivity ◽  
Structural Changes ◽  
Bulk Material ◽  
Thermal Contact ◽  
Measurement Techniques ◽  
High Sensitivity ◽  
Conductivity Measurements ◽  
Destructive Testing ◽  
Analysis And Design ◽  
Wide Range

In modern thermal analysis and design involving thermal transport in solid components it is necessary to apply different modeling of the thermal heat flow in bulk material and across solid surface interfaces either in shape of a layer or a solid-solid interface. Similar differences occur when applying different measurement techniques. Some techniques have been developed specifically for the purpose of performing measurements of bulk properties by removing the influence from thermal contact resistance between the measurement probe and the sample material. Thermal conductivity measurements on metal and ceramic objects of various geometries such as thin bars, thin sheets as well as coatings or layers are here described when using the Transient Plane Source technique. A summary overview of the recent developments of this technique, including its ability to be applied in measurement situations covering a wide range of length and time scales, is also presented. Structural changes in anisotropy can be recorded with high sensitivity by comparative measurements. The technique may be applied in situations requiring non-destructive testing, e.g. samples of particular geometry used for mechanical or tensile testing.

scholarly journals Immobilized Enzymes in Biosensor Applications

Materials ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 121 ◽  
Author(s):  
Hoang Hiep Nguyen ◽  
Sun Hyeok Lee ◽  
Ui Jin Lee ◽  
Cesar D. Fermin ◽  
Moonil Kim
Keyword(s):  
Point Of Care ◽  
Measurement Techniques ◽  
Diagnostic Testing ◽  
High Sensitivity ◽  
Immobilized Enzymes ◽  
Clinical Analysis ◽  
Safety Control ◽  
Wide Range ◽  
Piezoelectric Measurement ◽  
Innovative Techniques

Enzyme-based biosensing devices have been extensively developed over the last few decades, and have proven to be innovative techniques in the qualitative and quantitative analysis of a variety of target substrates over a wide range of applications. Distinct advantages that enzyme-based biosensors provide, such as high sensitivity and specificity, portability, cost-effectiveness, and the possibilities for miniaturization and point-of-care diagnostic testing make them more and more attractive for research focused on clinical analysis, food safety control, or disease monitoring purposes. Therefore, this review article investigates the operating principle of enzymatic biosensors utilizing electrochemical, optical, thermistor, and piezoelectric measurement techniques and their applications in the literature, as well as approaches in improving the use of enzymes for biosensors.

scholarly journals High Resolution Brillouin Sensing of Micro-Scale Structures

2018 ◽  
Vol 8 (12) ◽  
pp. 2572 ◽  
Author(s):  
Atiyeh Zarifi ◽  
Birgit Stiller ◽  
Moritz Merklein ◽  
Benjamin Eggleton
Keyword(s):  
Spatial Resolution ◽  
Measurement Techniques ◽  
High Sensitivity ◽  
Photonic Devices ◽  
Small Dimension ◽  
Detection Techniques ◽  
Micro Scale ◽  
Scale Structures ◽  
Distributed Measurement ◽  
On Chip

Brillouin distributed measurement techniques have been extensively developed for structural health monitoring using fibre optic nerve systems. The recent advancement in the spatial resolution capabilities of correlation-based Brillouin distributed technique have reached the sub-mm regime, making this approach a suitable candidate for monitoring and characterizing integrated photonic devices. The small dimension associated with the short length of these devices—on the order of the cm- and mm-scale—requires high sensitivity detection techniques and sub-mm spatial resolution. In this paper, we provide an overview of the different Brillouin sensing techniques in various micro-scale structures such as photonic crystal fibres, microfibres, and on-chip waveguides. We show how Brillouin sensing is capable of detecting fine transverse geometrical features with the sensitivity of a few nm and also extremely small longitudinal features on the order of a few hundreds of μ m . We focus on the technique of Brillouin optical correlation domain analysis (BOCDA), which enables such high spatial resolution for mapping the opto-acoustic responses of micro-scale waveguides.

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