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Spin-Torque-Driven Non-uniform Dynamics of an Antivortex Core in Truncated Astroid Shaped Nanomagnets

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arXiv 2025年

作者： Aykin, Ahmet Koral Piskin, Hasan Kocaman, Bayram Yanik, Cenk Karakas, Vedat Arpaci, Sevdenur Ozbay, Aisha Gokce Carpentieri, Mario Finocchio, Giovanni Celegato, Federica Tiberto, Paola Lendinez, Sergi Novosad, Valentine Hoffmann, Axel Ozatay, Ozhan Boğaziçi University Physics Department Istanbul Turkey Boğaziçi University Mechanical Engineering Department Istanbul Turkey Department of Fundamental Sciences Faculty of Engineering Alanya Alaaddin Keykubat University Antalya07450 Turkey Siirt University Department of Electrical and Electronics Engineering Siirt Turkey Northwestern University Department of Electrical and Computer Engineering EvanstonIL United States TUBITAK National Metrology Institute UME Kocaeli Turkey Politecnico di Bari Department of Electrical & Information Engineering Bari Italy University of Messina Department of Mathematical and Computer Sciences Physical Sciences and Earth Sciences Messina Italy Torino Italy Argonne National Laboratory Materials Science Division LemontIL United States University of Illinois Urbana-Champaign Department of Materials Science and Engineering Materials Research Laboratory UrbanaIL United States SUNUM Sabanci University Nanotechnology Research and Application Center Istanbul34956 Turkey

Spin textures that are not readily available in the domain structures of continuous magnetic thin films can be stabilized when patterned to micro/nano scales due to the dominant effect of dipolar magnetic interactions. Fabrication of such devices enables a thorough study of their RF dynamics excited by highly concentrated spin-polarized/pure-spin currents. For this purpose, in this study, we have employed a truncated astroid geometry to achieve stable magnetic antivortex core nucleation/annihilation which was detectable using the anisotropic magnetoresistance (AMR) at various temperatures. Furthermore, by depositing a soft magnetic thin film (20 nm thick permalloy) capped with a heavy-metal 2nm Pt layer, we were able to probe the spin orbit torque induced excitations accompanied by self-torque due to half-antivortex cores reminiscent of an isolated-antivortex, yielding GHz frequency oscillations with high quality factors (~50000). The observed RF oscillations can be attributed to a nonuniform domain wall oscillation mode close to the stable-antivortex core nucleation site as seen in micromagnetic simulations. This fundamental study of antivortex core response to spin currents is crucial for the assessment of their potential applications in high frequency spintronic devices such as reservoir computers. © 2025, CC BY-NC-ND.

关键词： Magnetic thin films

Dynamical phase-field model of cavity electromagnonic systems

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arXiv 2024年

作者： Zhuang, Shihao Zhu, Yujie Zhong, Changchun Jiang, Liang Zhang, Xufeng Hu, Jia-Mian Department of Materials Science and Engineering University of Wisconsin-Madison MadisonWI53706 United States Pritzker School of Molecular Engineering The University of Chicago ChicagoIL60637 United States Department of Electrical and Computer Engineering Northeastern University BostonMA02115 United States Department of Physics Northeastern University BostonMA02115 United States

Cavity electromagnonic system, which simultaneously consists of cavities for photons, magnons (quanta of spin waves), and acoustic phonons, provides an exciting platform to achieve coherent energy transduction among different physical systems down to single quantum level. Here we report a dynamical phase-field model that allows simulating the coupled dynamics of the electromagnetic waves, magnetization, and strain in 3D multiphase systems. As examples of application, we computationally demonstrate the excitation of hybrid magnon-photon modes (magnon polaritons), Floquet-induced magnonic Aulter-Townes splitting, dynamical energy exchange (Rabi oscillation) and relative phase control (Ramsey interference) between the two magnon polariton modes. The simulation results are consistent with analytical calculations based on Floquet Hamiltonian theory. Simulations are also performed to design a cavity electro-magno-mechanical system that enables the triple phonon-magnon-photon resonance, where the resonant excitation of a chiral, fundamental (n=1) transverse acoustic phonon mode by magnon polaritons is demonstrated. With the capability to predict coupling strength, dissipation rates, and temporal evolution of photon/magnon/phonon mode profiles using fundamental materials parameters as the inputs, the present dynamical phase-field model represents a valuable computational tool to guide the fabrication of the cavity electromagnonic system and the design of operating conditions for applications in quantum sensing, transduction, and communication. © 2024, CC BY.

关键词： Hamiltonians

Metalorganic chemical vapor deposition of β-(AlxGa1−x)2O3 thin films on (001) β-Ga2O3 substrates

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arXiv 2023年

作者： Bhuiyan, A.F.M. Anhar Uddin Meng, Lingyu Huang, Hsien-Lien Sarker, Jith Chae, Chris Mazumder, Baishakhi Hwang, Jinwoo Zhao, Hongping Department of Electrical and Computer Engineering The Ohio State University ColumbusOH43210 United States Department of Materials Science and Engineering The Ohio State University ColumbusOH43210 United States Department of Materials Design and Innovation University at Buffalo BuffaloNY14260 United States

Phase pure β-(AlxGa1−x)2O3 thin films are grown on (001) oriented β-Ga2O3 substrates via metalorganic chemical vapor deposition. By systematically tuning the precursor molar flow rates, the epitaxial growth of coherently strained β-(AlxGa1−x)2O3 films is demonstrated with up to 25% Al compositions as evaluated by high resolution x-ray diffraction. The asymmetrical reciprocal space mapping confirms the growth of coherent β-(AlxGa1−x)2O3 films (x 2O3 substrates. However, the alloy inhomogeneity with local segregation of Al along the (201) plane is observed from atomic resolution STEM imaging, resulting in wavy and inhomogeneous interfaces in the β-(AlxGa1−x)2O3/β-Ga2O3 superlattice structure. Room temperature Raman spectra of β-(AlxGa1−x)2O3 films show similar characteristics peaks as the (001) β-Ga2O3 substrate without obvious Raman shifts for films with different Al compositions. Atom probe tomography was used to investigate the atomic level structural chemistry with increasing Al content in the β-(AlxGa1−x)2O3 films. A monotonous increase in chemical heterogeneity is observed from the in-plane Al/Ga distributions, which was further confirmed via statistical frequency distribution analysis. Although the films exhibit alloy fluctuations, n-type doping demonstrates good electrical properties for films with various Al compositions. The determined valence and conduction band offsets at β-(AlxGa1−x)2O3/β-Ga2O3 heterojunctions using x-ray photoelectron spectroscopy reveal the formation of type-II (staggered) band alignment. Copyright © 2023, The Authors. All rights reserved.

关键词： X ray photoelectron spectroscopy

A Development of Object Detection System based on Deep Learning Approach to Support the Laparoscope Manipulating Robot (LMR)

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A Development of Object Detection System based on Deep Learn...

2022 International electrical engineering Congress, iEECON 2022

作者： Sonsilphong, Suphachoke Sonsilphong, Amornthep Hormdee, Daranee Khampitak, Kovit Khon Kaen University Data Science Health Informatics Program Academic Affairs Faculty of Medicine Khon Kaen Thailand Rajamangala University of Technology Isan Department of Electrical Engineering Khon Kean Thailand Khon Kaen University Embedded System RD Group Department of Computer Engineering Faculty of Engineering Khon Kean Thailand Khon Kean University Faculty of Medicine Department of Obstetrics and Gynecology Khon Kean Thailand

ISBN: (纸本)9781665402064

This paper presents the development of an object detection system based on the deep learning approach of computer vision to support the laparoscopic surgical robotic position control system. The system comprises two main phases, the training phase, and the real-time operating phase. In the training phase, a modified YOLOv4 algorithm is proposed to be adopted within the Darknet framework for training the weights of detection models. The best detection model is then selected to be assigned to the object detector in the real-time operating phase. The validation result of the detection model across the experiment datasets is 90% accuracy on average during the training phase. To validate the viability of real-time object detection, the proposed system was implemented in two test-cases of gynecologic surgery with the soft-body cadavers. © 2022 IEEE.

关键词： Laparoscopy

On-Demand Magnon Resonance Isolation in Cavity Magnonics

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arXiv 2024年

作者： Pishehvar, Amin Wang, Zhaoyou Zhu, Yujie Jiang, Yu Yan, Zixin Li, Fangxin Jornet, Josep M. Hu, Jia-Mian Jiang, Liang Zhang, Xufeng Department of Electrical and Computer Engineering Northeastern University BostonMA02115 United States Pritzker School of Molecular Engineering University of Chicago ChicagoIL60637 United States Department of Materials Science and Engineering University of Wisconsin - Madison MadisonWI53706 United States Department of Physics Northeastern University BostonMA02115 United States

Cavity magnonics is a promising field focusing the interaction between spin waves (magnons) and other types of signals. In cavity magnonics, the function of isolating magnons from the cavity to allow signal storage and processing fully in the magnonic domain is highly desired, but its realization is often hindered by the lack of necessary tunability on the interaction. This work shows that by utilizing the collective mode of two YIG spheres and adopting Floquet engineering, magnonic signals can be switched on-demand to a magnon dark mode that is protected from the environment, enabling a variety of manipulation over the magnon dynamics. Our demonstration can be scaled up to systems with an array of magnonic resonators, paving the way for large-scale programmable hybrid magnonic circuits. Copyright © 2024, The Authors. All rights reserved.

关键词： Spin waves

Real-time,in situ probing of gamma radiation damage with packaged integrated photonic chips

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Photonics Research 2020年第2期8卷 186-193页

作者： QINGYANG DU JEROME MICHON BINGZHAO LI DEREK KITA DANHAO MA HAIJIE ZUO SHAOLIANG YU TIAN GU ANURADHA AGARWAL MO LI JUEJUN HU Department of Materials Science&Engineering Massachusetts Institute of TechnologyCambridegMassachusetts 02139USA Department of Electrical and Computer Engineering University of WashingtonSeattleWashington 98195USA Department of Physics University of WashingtonSeattleWashington 98195USA

Integrated photonics is poised to become a mainstream solution for high-speed data communications and sensing in harsh radiation environments,such as outer space,high-energy physics facilities,nuclear power plants,and test fusion *** the impact of radiation damage in optical materials and devices is thus a prerequisite to building radiation-hard photonic systems for these *** this paper,we report real-time,in situ analysis of radiation damage in integrated photonic *** devices,integrated with an optical fiber array package and a baseline-correction temperature sensor,can be remotely interrogated while exposed to ionizing radiation over a long period without compromising their structural and optical *** also introduce a method to deconvolve the radiation damage responses from different constituent materials in a *** approach was implemented to quantify gamma radiation damage and post-radiation relaxation behavior of SiO2-cladded SiC photonic *** findings suggest that densification induced by Compton scattering displacement defects is the primary mechanism for the observed index change in ***,post-radiation relaxation in amorphous SiC does not restore the original pre-irradiated structural state of the *** results further point to the potential of realizing radiation-hard photonic device designs taking advantage of the opposite signs of radiation-induced index changes in SiC and SiO2.

关键词： scattering damage relaxation

Passive frequency-conversion imaging from the near-infrared to the visible

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Passive frequency-conversion imaging from the near-infrared ...

Conference on Lasers and Electro-Optics (CLEO)

作者： Demeng Feng Rabeeya Hamid Emma Belliveau Manchen Hu Pournima Narayanan Jad Salman Chenghao Wan Bryan E. Rubio-Perez Daniel N. Congreve Mikhail A. Kats Department of Electrical and Computer Engineering University of Wisconsin-Madison Madison WI USA Department of Electrical Engineering Stanford University Stanford CA USA Department of Chemistry Stanford University Stanford CA USA Department of Materials Science and Engineering University of Wisconsin-Madison Madison WI USA Department of Physics University of Wisconsin-Madison Madison WI USA

We demonstrate a passive frequency-conversion imaging system that converts near-infrared images into visible images, enabling near-infrared imaging with the naked eye or a conventional visible camera.

ISBN: (纸本)9781957171258

关键词： Diode lasers Image quality Near infrared radiation Quantum efficiency Ultraviolet radiation Visible light

Enhanced Imaging of Electronic Hot Spots Using Quantum Squeezed Light

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arXiv 2024年

作者： An, Haechan Amiri, Ali Najjar Goronzy, Dominic P. Garcia Wetten, David A. Bedzyk, Michael J. Shakouri, Ali Hersam, Mark C. Hosseini, Mahdi Elmore Family School of Electrical and Computer Engineering Purdue University West LafayetteIN47907 United States Department of Electrical and Computer Engineering and Applied Physics Northwestern University EvanstonIL60208 United States Department of Materials Science and Engineering Northwestern University EvanstonIL60208 United States Department of Physics and Astronomy Northwestern University EvanstonIL60208 United States Department of Chemistry Northwestern University EvanstonIL60208 United States

Detecting electronic hot spots is important for understanding the heat dissipation and thermal management of electronic and semiconductor devices. Optical thermoreflective imaging is being used to perform precise temporal and spatial imaging of heat on wires and semiconductor materials. We apply quantum squeezed light to perform thermoreflective imaging on micro-wires, surpassing the shot-noise limit of classical approaches. We obtain a far-field temperature sensing accuracy of 42 mK after 50 ms of averaging and show that a 256×256 pixel image can be constructed with such sensitivity in 10 minutes. We can further obtain single-shot temperature sensing of 1.6 K after only 10 µs of averaging enabling dynamical study of heat dissipation. Not only do the quantum images provide accurate spatio-temporal information about heat distribution, but the measure of quantum correlation provides additional information, inaccessible by classical techniques, that can lead to a better understanding of the dynamics. We apply the technique to both Al and Nb microwires and discuss the applications of the technique in studying electron dynamics at low temperatures. © 2024, CC BY.

关键词： Shot noise

Microwave-Induced Cooling in Double Quantum Dots: Achieving Millikelvin Temperatures to Reduce Thermal Noise around Spin Qubits

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arXiv 2024年

作者： Vashaee, Daryoosh Abouie, Jahanfar Department of Materials Science & Engineering North Carolina State University RaleighNC27606 United States Department of Electrical & Computer Engineering North Carolina State University RaleighNC27606 United States Department of Physics Institute for Advanced Studies in Basic Sciences Zanjan45137-66731 Iran

Spin qubits in gate-defined quantum dots are emerging as a leading technology due to their scalability and long coherence times. However, maintaining these qubits at ultra-low temperatures typically requires complex cryogenic systems. This paper proposes a novel gate-defined double quantum dot (DQD) cooling system using microwave-induced state depopulation and phonon filtering to achieve local temperatures below 10 mK at a bath temperature of 1 K. The system utilizes microwave-induced state depopulation and phonon filtering, combined with fast cyclic detuning of the quantum dot on-site energies and Rabi oscillations, to efficiently transfer thermal populations to the ground state, thereby surpassing natural thermal transition rates. The cooling cycle involves adjusting gate potentials to drive the system through adiabatic and diabatic transitions, complemented by microwave pulses resonant with specific energy level differences. This mechanism continuously pumps population from excited states into the ground state, effectively reducing the system's temperature. Numerical calculations demonstrate the feasibility of achieving these low local temperatures, with detailed analysis showing the sensitivity of cooling performance to detuning energy, magnetic field strength, and diabatic return time. Copyright © 2024, The Authors. All rights reserved.

关键词： Semiconductor quantum dots