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Antiferromagnetic Hysteresis above the Spin Flop Field

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arXiv 2021年

作者： Grzybowski, M.J. Schippers, C.F. Gomonay, O. Rubi, K. Bal, M.E. Zeitler, U. Koziol-Rachwal, A. Szpytma, M. Janus, W. Kurowska, B. Kret, S. Gryglas-Borysiewicz, M. Koopmans, B. Swagten, H.J.M. Department of Applied Physics Eindhoven University of Technology PO Box 513 Eindhoven5600 MB Netherlands Faculty of Physics University of Warsaw Pasteura 5 Warsaw Poland Institute of Physics Johannes Gutenberg-University Mainz Mainz55128 Germany Radboud University Nijmegen6525 ED Netherlands Faculty of Physics and Applied Computer Science AGH University of Science and Technology Kraków30-059 Poland Institute of Physics Polish Academy of Sciences Lotników 32/46 Warsaw Poland

Magnetocrystalline anisotropy is essential in the physics of antiferromagnets and commonly treated as a constant, not depending on an external magnetic field. However, we demonstrate that in CoO the anisotropy should necessarily depend on the magnetic field, which is shown by the spin Hall magnetoresistance of the CoO | Pt device. Below the Néel temperature CoO reveals a spin-flop transition at 240 K at 7.0 T, above which a hysteresis in the angular dependence of magnetoresistance unexpectedly persists up to 30 T. This behavior is shown to agree with the presence of the unquenched orbital momentum, which can play an important role in antiferromagnetic spintronics. © 2021, CC BY.

关键词： Magnetocrystalline anisotropy

Comparative Assessment of Radioactivity Concentration in Sweet Potatoes from Different Geopolitical Zones of Nigeria

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Comparative Assessment of Radioactivity Concentration in Swe...

science, Engineering and Business for Sustainable Development Goals (SEB-SDG), International Conference on

作者： Adegbenro Sunday Ajani Godwin Babatunde Egbeyale Olaide Eyiwumi Shogo Charity Segun Odeyemi Abdullahi Nasir Galadima Peter Olaoluwa Oyero Department of Physics and Materials Science Faculty of Pure and Applied Sciences Kwara State University Ilorin Kwara State Nigeria Department of Electrical Electronics Engineering School of Engineering and Engineering Technology Federal University of Technology Akure Ondo State Nigeria Department of Basic Sciences Adeleke University Ede Osun State Nigeria

Evaluation of the specific activity of radioactivity in tubers is an important tool in the assessment of human internal exposure to radiation through ingestion. In this research, the activity concentrations of natural radionuclides 40 K, 238 U and 232 Th in sweet potato samples taken from different farm lands in the six geopolitical zones of Nigeria were determined by means of gamma spectrometry. Using standard calibrated NaI (TI) and shielded detector coupled to a computer resident quantum MCA2100R Multichannel analyzer for 36,000 s. The activities were estimated to be 526.39 ± 51.40, 8.55 ± 1.76 and 1.14 ± 0.42Bq/kg respectively for 40 K, 238 U and 232 Th. The estimated daily intake through potato diet are 6.6622, 4.6860, 4.6748, 2.75103, 2.7453, and 2.3983 Bq.d −1 for South-East (Abia), South-South(Edo), South-West(Oyo), North-Central (Kwara), North-West (Sokoto), and North-East (Adamawa) respectively. Findings showed that potato plants uptake and transport radionuclides from the soil by the root system. It also showed that 40 K is the most radionuclides contaminant presents in the farm soil where the potato plants were grown. The daily intake of radionuclides was also observed to be highest in 40 K. This may be due to the use of phosphate rich fertilizer in the farmlands where they were grown. The overview of the research showed that the annual effective doses due to potato diet, at this present rate, pose no significant threat to the public.

关键词： Spectroscopy Quantum computing Detectors Soil Sustainable development Surges Standards

Disclosing the Nature of Asymmetric Interface Magnetism in Co/Pt Multilayers (vol 14, pg 12776, 2022)

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ACS applied MATERIALS & INTERFACES 2022年第20期14卷 24069-24069页

作者： Verna, Adriano Alippi, Paola Offi, Francesco Barucca, Gianni Varvaro, Gaspare Agostinelli, Elisabetta Albrecht, Manfred Rutkowski, Bogdan Ruocco, Alessandro Paoloni, Daniele Valvidares, Manuel Laureti, Sara Dipartimento di Scienze Università degli Studi Roma Tre Via della Vasca Navale 84 Roma I-00146 Italy ENEA-FSN-Fiss-SNI Casaccia R. C. Via Anguillarese 301 Roma 00123 Italy Istituto di Struttura della Materia CNR Monterotondo Scalo Roma 00015 Italy Dipartimento SIMAU Università Politecnica Delle Marche Via Brecce Bianche Ancona 60121 Italy Istituto di Struttura della Materia CNR nM-Lab Monterotondo Scalo Roma 00015 Italy Institute of Physics University of Augsburg Universitätsstraße 1 Nord Augsburg D-86159 Germany Faculty of Metals Engineering and Industrial Computer Science AGH University of Science and Technology Al. A. Mickiewicza 30 Kraków 30-059 Poland ALBA Synchrotron Light Source Cerdanyola del Vallès Barcelona E-08290 Spain

Nowadays, a wide number of applications based on magnetic materials rely on the properties arising at the interface between different layers in complex heterostructures engineered at the nanoscale. In ferromagnetic/heavy metal multilayers, such as the [Co/Pt]Nand [Co/Pd]Nsystems, the magnetic proximity effect was demonstrated to be asymmetric, thus inducing a magnetic moment on the Pt (Pd) layer that is typically higher at the top Co/Pt(Pd) interface. In this work, advanced spectroscopic and imaging techniques were combined with theoretical approaches to clarify the origin of this asymmetry both in Co/Pt trilayers and, for the first time, in multilayer systems that are more relevant for practical applications. The different magnetic moment induced at the Co/Pt interfaces was correlated to the microstructural features that are in turn affected by the growth processes that induce a different intermixing during the film deposition, thus influencing the interface magnetic profile.

关键词： Interfaces Platinum Layers Magnetic properties Optical properties

A geothermal multigeneration system integrating an ORC configuration with an open-feed heater for electricity/H 2 /cooling production: Techno-economic optimization using a genetic algorithm

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International Journal of Refrigeration 2025年 177卷 141-155页

作者： Lel Chang Ali Basem Ahmad Almadhor Dyana Aziz Bayz Sarminah Samad Mohamed Ayadi Essam R. El-Zahar Barno Abdullaeva Abdulrahman Alansari H.Elhosiny Ali School of Economics and Management Anhui University of Science and Technology Taifeng Road 168 Huainan 232001 Anhui Province PR China Faculty of Engineering Warith Al-Anbiyaa University Karbala 56001 Iraq Department of Computer Engineering and Networks College of Computer and Information Sciences Jouf University Saudi Arabia Department of Petroleum Engineering College of Engineering Knowledge university Erbil Iraq Department of Petroleum Engineering Al-Kitab University Altun Kupri Iraq Department of Management College of Business Administration Princess Nourah bint Abdulrahman University Riyadh 11671 Saudi Arabia Department of Mathematics College of Science Majmaah University Al-Majmaah 11952 Saudi Arabia Department of Mathematics College of Science and Humanities in Al-Kharj Prince Sattam bin Abdulaziz University Al-Kharj 11942 Saudi Arabia Department of Basic Engineering Sciences Faculty of Engineering Menoufia University Shebin El-Kom 32511 Egypt Department of Mathematics and Information Technologies Vice-Rector for Scientific Affairs Tashkent State Pedagogical University Tashkent Uzbekistan Department of Mechanical Engineering College of Engineering University of Business and Technology Jeddah 21361 Saudi Arabia Physics Department Faculty of Science King Khalid University P.O. Box 9004 Abha Saudi Arabia

This research presents a novel geothermal-based multigeneration framework engineered to supply electric energy, hydrogen gas, and chilled water. The framework incorporates an organic Rankine cycle (ORC) with an open feed heater (OFH), a Kalina cycle (KC), an absorption refrigeration cycle (ARC), and a PEM electrolyzer (PEME). A comprehensive thermodynamic and economic evaluation is performed, followed by a multi-objective optimization using NSGA-II in MATLAB to maximize exergetic performance and minimize cost. Key parameters include geothermal fluid temperature, mass flow rate, ORC turbine inlet temperature, and evaporator pinch point temperature difference (PPTD). The ORC exhibits the highest exergy destruction (42 %), trailed by the KC (26 %) and PEME (19 %), while the ARC contributes the least (13 %). Elevating geothermal fluid temperature significantly enhances exergy efficiency and hydrogen output, although costs increase. Enhancing the mass flow rate from 5 kg/s to 18 kg/s substantially improves power generation and cooling capacity but diminishes efficiency and escalates equipment expenses. Increasing the evaporator PPTD reduces power output and hydrogen production yet increases chilled water generation and slightly lowers the overall cost rate. Under optimal conditions, the plant achieves the exergetic performance of 38.56 % and a cost rate of 17.11 $/h, highlighting the potential of this integrated approach to deliver sustainable, cost-effective solutions for electricity generation, refrigeration, and hydrogen production from geothermal resources.

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Beyond circular-arc graphs - recognizing lollipop graphs and medusa graphs

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arXiv 2022年

作者： Çağirici, Deniz Ağaoğlu Çağirici, Onur Derbisz, Jan Hartmann, Tim A. Hliněný, Petr Kratochvíl, Jan Krawczyk, Tomasz Zeman, Peter Masaryk University Brno Czech Republic Toronto Metropolitan University Toronto Canada Theoretical Computer Science Department Faculty of Mathematics and Computer Science Jagiellonian University Kraków Poland RWTH Aachen University Aachen Germany Department of Applied Mathematics Faculty of Mathematics and Physics Charles University Prague Czech Republic Institut de Mathématiques University of Neuchâtel Switzerland

In 1992 Biró, Hujter and Tuza introduced, for every fixed connected graph H, the class of H-graphs, defined as the intersection graphs of connected subgraphs of some subdivision of H. Such classes of graphs are related to many known graph classes: for example, K2-graphs correspond to interval graphs, K3-graphs correspond to circular-arc graphs, the union of T-graphs, where T ranges over all trees, correspond to chordal graphs. Recently, quite a lot of research has been devoted to understanding the tractability border for various computational problems, such as recognition or isomorphism testing, in classes of H-graphs for different graphs H. In this work we undertake this research topic, focusing on the recognition problem. Chaplick, Töpfer, Voborník, and Zeman showed an XP-algorithm testing whether a given graph is a T-graph, where the parameter is the size of the tree T. In particular, for every fixed tree T the recognition of T-graphs can be solved in polynomial time. Tucker showed a polynomial time algorithm recognizing K3-graphs (circular-arc graphs). On the other hand, Chaplick at al. showed also that recognition of H-graphs is NP-hard if H contains two different cycles sharing an edge. The main two results of this work narrow the gap between the NP-hard and P cases of H-graphs recognition. First, we show that recognition of H-graphs is NP-hard when H contains two different cycles. On the other hand, we show a polynomial-time algorithm recognizing L-graphs, where L is a graph containing a cycle and an edge attached to it (L is called a lollipop and L-graphs are called lollipop graphs). Clearly, the class of lollipop graphs extends the class of circular-arc graphs. Our work leaves open the recognition problems of M-graphs for every unicyclic graph M different from a cycle and a lollipop. Other results of this work, which shed some light on the cases that remain open, are as follows: • recognition of M-graphs, where M is a fixed unicyclic graph, admits a polynom

关键词： Polynomial approximation

Research on the In uence of Small Changes in the Chemical Composition on Changes in the Environment of Fe Atoms in Rapid-Quenched Alloys

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Research on the In uence of Small Changes in the Chemical Co...

作者： Jeż, K. Pietrusiewicz, P. Sandu, A.V. SALLEh, M.A.A.M. Nabialek, M.M. Jaruga, T. Faculty of Civil Engineering Czestochowa University of Technology Akademicka 3 Czestochowa42-200 Poland Department of Physics Faculty of Production Engineering and Materials Technology Czestochowa University of Technology al. Armii Krajowej 19 Czestochowa42-200 Poland Faculty of Material Science and Engineering Gheorghe Asachi Technical University 64 Dumitru Mangeron Blvd Iasi700050 Romania Academy of Romanian Scientists 54 Splaiul Independentei St. Sect. 5 Bucharest050094 Romania Center of Excellence Geopolymer and Green Technology Universiti Malaysia Perlis Taman Muhibbah Perlis Arau02600 Malaysia Department of Technology and Automation Faculty of Mechanical Engineering and Computer Science Czestochowa University of Technology al. Armii Krajowej 19c Czestochowa42-200 Poland

Rapid-quenched Fe-based alloys may show hard or soft magnetic properties depending on the chemical composition and structure of the alloy. One of the most sensitive methods of studying the structure and, indirectly, magnetic properties is Mössbauer spectroscopy. Using this method, it is possible to determine the surroundings of Fe atoms and to identify crystalline phases in the volume of the alloy. The distributions of hyper ne eld induction supplemented with measurements of saturation magnetization as a function of the external magnetic eld allow us to explain signi cant differences in magnetic properties also within the amorphous structure. The paper presents the results of research on the structure and magnetic properties of rapid-quenched FeNbYHfB alloys. It was found that slight changes in the chemical composition affect the surroundings of Fe atoms and the density of the alloy, which correlates with the change in the value of the coercive eld and saturation magnetization of rapid-quenched alloys. © 2025 Polska Akademia Nauk. All rights reserved.

关键词： Saturation magnetization

An on-chip platform for multi-degree-of-freedom control of two-dimensional quantum and nonlinear materials

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arXiv 2023年

作者： Tang, Haoning Wang, Yiting Ni, Xueqi Watanabe, Kenji Taniguchi, Takashi Jarillo-Herrero, Pablo Fan, Shanhui Mazur, Eric Yacoby, Amir Cao, Yuan School of Engineering and Applied Sciences Harvard University CambridgeMA02138 United States National Institute for Materials Science Namiki 1-1 Ibaraki Tsukuba305-0044 Japan Department of Physics Massachusetts Institute of Technology CambridgeMA02139 United States Department of Applied Physics Ginzton Laboratory Stanford University StanfordCA94305 United States Department of Physics Faculty of Art and Sciences Harvard University CambridgeMA02138 United States Society of Fellows Harvard University CambridgeMA02138 United States Department of Electrical Engineering and Computer Science University of California at Berkeley BerkeleyCA94720 United States

Two-dimensional materials (2DM) and their derived heterostructures have electrical and optical properties that are widely tunable via several approaches, most notably electrostatic gating and interfacial engineering such as twisting. While electrostatic gating is inherently simple and has thus been ubiquitously employed on 2DM, being able to tailor the interfacial properties in a similar real-time manner represents the next leap in our ability to modulate the underlying physics and build exotic quantum devices with 2DM1–6. However, all existing approaches rely on external machinery such as scanning microscopes, which often limit their scope of applications, and there is currently no means of tuning a 2D interface that has the same accessibility and scalability as device-level electrostatic gating. Here, we demonstrate the first on-chip platform designed for 2D materials with in situ tunable interfacial properties, utilizing a microelectromechanical system (MEMS). Each of these compact, cost-effective, and versatile devices is a standalone micromachine that allows voltage-controlled approaching, twisting, and pressurizing of two sheets of 2DM with high accuracy. As a demonstration, we engineer various flavours of synthetic topological singularities, known as half-skyrmions or merons, in the nonlinear optical susceptibility of twisted hexagonal boron nitride (h-BN)7–10, via simultaneous control of twist angle and interlayer separation. The chirality of the resulting moiré pattern further induces a strong circular dichroism in the second-harmonic generation. A potential application of this topological nonlinear susceptibility is to create integrated light sources that have widely and real-time tunable polarization, which we demonstrate experimentally. As a perspective, a quantum version of the same principle can generate entangled photon pairs with tunable entanglement characteristics. Our invention pushes the boundary of currently available technologies for manipulati

关键词： III-V semiconductors

Hyperspectral Brain Tissue Classification using a Fast and Compact 3D CNN Approach

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Hyperspectral Brain Tissue Classification using a Fast and C...

International Image Processing, Applications and Systems Conference (IPAS)

作者： Hamail Ayaz David Tormey Ian McLoughlin Muhammad Ahmad Saritha Unnikrishnan Faculty of Engineering and Design and Mathematical Modelling and Intelligent Systems for Health and Environment Atlantic Technological University Sligo Ireland Faculty of Engineering and Design Centre for Precision Engineering Materials and Manufacturing Research (PEM) Atlantic Technological University Sligo Ireland Department of Computer Science and Applied Physics Atlantic Technological University Galway Ireland Department of Computer Science National University of Computer and Emerging Sciences Chiniot Pakistan

ISBN: (纸本)9781665462204

Glioblastoma (GB) is a malignant brain tumor and requires surgical resection. Although complete resection of GB improves prognosis, supratotal resection may cause neurological abnormalities. Therefore, intraoperative tissue classification techniques are needed to delineate infected tumor regions to remove reoccurrences. To delineate the affected regions, surgeons mostly rely on traditional magnetic resonance imaging (MRI) which often lacks accuracy and precision due to the brain-shift phenomenon. Hyperspectral Imaging (HSI) is a noninvasive advanced optical technique and has the potential to classify tissue cells accurately. However, HSI tumor classification is challenging due to overlapping regions, high interclass similarity, and homogeneous information. Additionally, HSI models using 2D Convolutional Neural Network (CNN) models works with spectral information eliminating spatial features and 3D followed by 2D hybrid model lacks abstract level spatial information. Therefore, in this study, we have used a minimal layer 3D CNN model to classify the GB tumor region from normal tissues using an intraoperative VivoHSI dataset. The HSI data have normal tissue (NT), tumor tissue (TT), hypervascularized tissue or blood vessels (BV), and background (BG) tissue cells. The proposed 3D CNN model consists of only two 3D layers using limited training samples (20%), which are further divided into 50% for training and 50% for validation and blind tested (80%) on the rest of the data. This study outperformed then state-of-the-art hybrid architecture by achieving an overall accuracy of 99.99%.

关键词： Training Solid modeling Three-dimensional displays Magnetic resonance imaging Surgery Brain modeling Data models

Entanglement generation from athermality

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arXiv 2024年

作者： de Oliveira Junior, A. Son, Jeongrak Czartowski, Jakub Ng, Nelly H.Y. Center for Macroscopic Quantum States bigQ Department of Physics Technical University of Denmark Fysikvej 307 Kgs. Lyngby2800 Denmark School of Physical and Mathematical Sciences Nanyang Technological University Singapore637371 Singapore Doctoral School of Exact and Natural Sciences Jagiellonian University Kraków30-348 Poland Faculty of Physics Astronomy and Applied Computer Science Jagiellonian University Kraków30-348 Poland

We investigate the thermodynamic constraints on the pivotal task of entanglement generation using out-of-equilibrium states through a model-independent framework with minimal assumptions. We establish a necessary and sufficient condition for a thermal process to generate bipartite qubit entanglement, starting from an initially separable state. Consequently, we identify the set of system states that cannot be entangled, when no external work is invested. In the regime of infinite temperature, we analytically construct this set;while for finite temperature, we provide a simple criterion to verify whether any given initial state is or is not entanglable. Furthermore, we provide an explicit construction of the future thermal cone of entanglement - the set of entangled states that a given separable state can thermodynamically evolve to. We offer a detailed discussion on the properties of this cone, focusing on the interplay between entanglement and its volumetric properties. We conclude with several key remarks on the generation of entanglement beyond two-qubit systems, and discuss its dynamics in the presence of dissipation. © 2024, CC BY.

关键词： Volumetric analysis