147 research outputs found
Electric field-induced creation and directional motion of domain walls and skyrmion bubbles
Magnetization dynamics driven by an electric field could provide long-term
benefits to information technologies because of its ultralow power consumption.
Meanwhile, the Dzyaloshinskii-Moriya interaction in interfacially asymmetric
multilayers consisting of ferromagnetic and heavy-metal layers can stabilize
topological spin textures, such as chiral domain walls, skyrmions, and skyrmion
bubbles. These topological spin textures can be controlled by an electric
field, and hold promise for building advanced spintronic devices. Here, we
present an experimental and numerical study on the electric field-induced
creation and directional motion of topological spin textures in magnetic
multilayer films and racetracks with thickness gradient and interfacial
Dzyaloshinskii-Moriya interaction at room temperature. We find that the
electric field-induced directional motion of chiral domain wall is accompanied
with the creation of skyrmion bubbles at certain conditions. We also
demonstrate that the electric field variation can induce motion of skyrmion
bubbles. Our findings may provide opportunities for developing skyrmion-based
devices with ultralow power consumption.Comment: 26 pages, 6 figure
Dynamics of interacting skyrmions in magnetic nano-track
Controlling multiple skyrmions in nanowires is important for their
implementation in racetrack memory or neuromorphic computing. Here, we report
on the dynamical behavior of two interacting skyrmions in confined devices with
a comparison to a single skyrmion case. Although the two skyrmions shrink near
the edges and follow a helical path, their behavior is different. Because the
leading skyrmion is between the edge and the trailing one, its size is reduced
further and collapses at a lower current density compared to the single
skyrmion case. For higher current density, both skyrmions are annihilated with
a core-collapse mechanism for the leading one followed by a bubble-collapse
mechanism for the trailing one
Motivational, emotional and memorable dimensions of non-Muslim tourists’ halal food experiences
Purpose: This study aims to explore non-Muslim tourists’ general halal food preferences, motivations for tasting halal food during their recent trips, positive and negative emotions and memorable dimensions associated with their recent halal food experiences after returning from holiday. Design/methodology/approach: Data were collected using the authors’ personal networks and Amazon Mechanical Turk (MTurk) using a questionnaire. An email containing a link to the questionnaire was sent to the authors’ personal networks and posted on MTurk in January 2021. Findings: Of the 311 non-Muslim respondents, more than half considered themselves as food neophiliacs and considered halal food experiences as imperative whilst travelling. However, tasting halal food was not a major travel motivation. Novelty and taste were the two main motivations for tasting halal food whilst at a tourism destination. Emotions elicited by halal food experiences focussed on “joy” and “love”. The proposed conceptual framework for memorable halal food experiences comprises several dimensions: taste, spending time with family and friends, novelty, quality and safety, hospitality, ambience (setting/servicescape) and experiencing others’ culture through food. Originality/value: This is one of the first studies to explore non-Muslim tourists’ motives, emotions and memorable dimensions of halal food experiences
Persistently high HIV seroprevalence among adult tuberculosis patients at a tertiary care centre in Delhi
Background & Objective: This study was designed to estimate HIV seroprevalence among tuberculosis patients presenting to tertiary care centre in Delhi. Methods: Cross-sectional prevalence study among all patients presenting to the inpatient and outpatient departments of All India Institute of Medical Sciences (AIIMS), New Delhi, and receiving anti-tuberculosis treatment from May 2003 to April 2005. Results: Of the 448 patients who presented to the TB clinic during the study period, 23 (5.1%) were previously tested HIV-positive. An additional 21 patients (4.6%) refused testing, and 30 (6.7%) were lost to follow up. Of the remaining 374 patients who consented to testing, 31 (8.3%) were found to be HIV-positive. Risk factors for HIV seropositivity included high-risk sexual behaviours (48% in HIV-TB co-infected vs. 6% in TB infected patients, P<0.001) and history of blood transfusion (23% vs. 5%; P=0.002). Interpretation & Conclusion: Previous studies from the same hospital published in 2000 and 2003 reported HIV seroprevalence among TB patients to be 0.4 and 9.4 per cent respectively. The current study documents a persistently high seropositivity among TB patients. These results emphasize the acute need for improved detection and treatment for HIV among TB patients in northern India
Diode Like Attributes in Magnetic Domain Wall Devices via Geometrical Pinning for Neuromorphic Computing
Neuromorphic computing (NC) is considered as a potential vehicle for
implementing energy-efficient artificial intelligence (AI). To realize NC,
several materials systems are being investigated. Among them, the spin-orbit
torque (SOT) -driven domain wall (DW) devices are one of the potential
candidates. To implement these devices as neurons and synapses, the building
blocks of NC, researchers have proposed different device designs. However, the
experimental realization of DW device-based NC is only at the primeval stage.
In this study, we have proposed and investigated pine-tree-shaped DW devices,
based on the Laplace force on the elastic DWs, for achieving the synaptic
functionalities. We have successfully observed multiple magnetization states
when the DW was driven by the SOT current. The key observation is the
asymmetric pinning strength of the device when DW moves in two opposite
directions (defined as, xhard and xeasy). This shows the potential of these DW
devices as DW diodes. We have used micromagnetic simulations to understand the
experimental findings and to estimate the Laplace pressure for various design
parameters. The study leads to the path of device fabrication, where synaptic
properties are achieved with asymmetric pinning potential
Experimental investigation and statistical analysis of additively manufactured onyx-carbon fiber reinforced composites
This is the peer reviewed version of the following article published in final form at https://doi.org/10.1002/app.50338. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.Availability of additive manufacturing (AM) has influenced the scientific community to improve on production and versatility of the components created with several associated technologies. Adding multiple substances through superimposing levels is considered as a part of three-dimensional (3D) printing innovations to produce required products. These technologies are experiencing an increase in development nowadays. It requires frequently adding substance and has capacity to fabricate extremely complex geometrical shapes. However, the fundamental issues with this advancement include alteration of capacity to create special products with usefulness and properties at an economically viable price. In this study, significant procedural parameters: layer designs/ patterns (hexagonal, rectangular and triangular) and infill densities (30, 40 and 50%) were considered to investigate into their effects on mechanical behaviors of fused deposition modeling (FDM) or 3D-printed onyx-carbon fiber reinforced composite specimens, using a high-end 3D printing machine. Mechanical (tensile and impact) properties of the printed specimens were conclusively analyzed. From the results obtained, it was observed that better qualities were achieved with an increased infill density, and rectangular-shaped design exhibited an optimum or maximum tensile strength and energy absorption rate, when compared with other counterparts. The measurable relapse conditions were viably evolved to anticipate the real mechanical qualities with an accuracy of 96.4%. In comparison with other patterns, this was more closely predicted in the rectangular design, using regression models. The modeled linear regression helps to define the association of two dependent variables linked with properties of the dissimilar composite material natures. The models can further predict response of the quantities before and also guide practical applications.Peer reviewedFinal Accepted Versio
Achieving High Aspect Ratio of Track Length to Width in Molds for Discrete Track Recording Media
Discrete track media (DTM) fabricated by nanoimprint lithography (NIL) is considered as a potential technology for future hard disk drives (HDD). In the fabrication of a master mold for NIL, patterning the resist tracks with a narrow distribution in the width is the first critical step. This paper reports the challenges involved in the fabrication of high aspect ratio discrete tracks on Polymethylmethacrylate (PMMA) resist by means of electron beam lithography. It was observed that fabrication parameters applied for successful patterning of discrete tracks in nanoscale length were not directly suitable for the patterning of discrete tracks in micron scale. Hence different approaches such as thick layer resist coating, introducing of post exposure baking process, and varying of exposure parameters were used in order to achieve uniform sharp discrete tracks in micron scale length on the resist. The optimal parameters were used to pattern 20 μm long tracks with 70 nm track pitch on the resist
Achieving High Aspect Ratio of Track Length to Width in Molds for Discrete Track Recording Media
Discrete track media (DTM) fabricated by nanoimprint lithography (NIL) is considered as a potential technology for future hard disk drives (HDD). In the fabrication of a master mold for NIL, patterning the resist tracks with a narrow distribution in the width is the first critical step. This paper reports the challenges involved in the fabrication of high aspect ratio discrete tracks on Polymethylmethacrylate (PMMA) resist by means of electron beam lithography. It was observed that fabrication parameters applied for successful patterning of discrete tracks in nanoscale length were not directly suitable for the patterning of discrete tracks in micron scale. Hence different approaches such as thick layer resist coating, introducing of post exposure baking process, and varying of exposure parameters were used in order to achieve uniform sharp discrete tracks in micron scale length on the resist. The optimal parameters were used to pattern 20 μm long tracks with 70 nm track pitch on the resist
Nanoscale Modification of Magnetic Properties for Effective Domain Wall Pinning
Magnetic domain wall memory technology, wherein the information is stored in magnetic domains of multiple magnetic nanowires, is a potential concept proposed to store the large amount of digital data in the near future, which is generated due to the widespread use of social media and computing devices. However, one of the technological challenges which remains to be solved in domain wall memory is the controllable pinning of the domain walls at the nanometer scale. Here, we demonstrate the possibility to stabilize domain walls with nanoscale modification of magnetic properties by using thermal diffusion of elements from crossbar configuration. We have inspected and evaluated the magnetic properties of the nanowires using Kerr microscopy. The pinning field induced by Cr diffusion of our Ni80Fe20 nanowire was estimated to be about 8 kA/m as determined from minor loop (magnetoresistance vs. magnetic field) measurements. The proposed concept can potentially be used in future domain wall memory applications. © 2018 Elsevier B.V.We gratefully acknowledge Nanyang Technological University Start-Up Grant, AcRF-Tier 1 grant RG163/15 of Ministry of Education Singapore, and NTU-JSPS grant offered by Nanyang Technological University, Singapore and Japan Society for the Promotion of Science for the funding and support of this research
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