Article
Chemistry, Physical
Junta Igarashi, Wei Zhang, Quentin Remy, Eva Diaz, Jun-Xiao Lin, Julius Hohlfeld, Michel Hehn, Stephane Mangin, Jon Gorchon, Gregory Malinowski
Summary: The authors demonstrate ultrafast magnetization reversal induced by light in rare-earth-free spin valves of [Pt/Co]/Cu/[Co/Pt] within a picosecond. The discovery of spin-transfer torque (STT) allowed the control of magnetization direction in nanoseconds using electrical current. Ultrashort optical pulses have been used to manipulate the magnetization of ferrimagnets in picoseconds by driving the system out of equilibrium. In this study, the authors show ultrafast magnetization reversal induced by light in commonly used [Pt/Co]/Cu/[Co/Pt] spin valves for STT switching, bridging concepts from spintronics and ultrafast magnetism.
Article
Physics, Multidisciplinary
Christos Thanos, Ioannis Panagiotopoulos
Summary: Micromagnetic simulations are used to study resonances and microwave assisted magnetic switching (MAS) in two-phase Co/CoPt nanowires. The nucleation, interfacial domain wall pinning, and propagation processes are well distinguished and play a role in the system. The coupling strength varies to cover different hysteresis curves. Interfacial resonances play an important role in MAS, allowing for optimal conditions with low MAS frequencies and dc applied fields while balancing low field usage and short reversal time.
Article
Chemistry, Multidisciplinary
Yanfei Zhu, Lidan Guo, Jun Guo, Luyang Zhao, Chunyan Li, Xueying Qiu, Yang Qin, Xianrong Gu, Xiangnan Sun, Zhiyong Tang
Summary: Quantum-confined atomically precise metal nanoclusters (MNCs) are a new type of inorganic-organic hybrid semiconductor that have been widely used in chemical sensing, optical imaging, biomedicine and catalysis. Researchers have successfully designed and fabricated a spin valve (SV) based on MNCs, demonstrating remarkable magnetoresistance values and the ability to change the spin-dependent transport properties by altering the atomic structure of the MNCs.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Multidisciplinary
Karl Ridier, William Nicolazzi, Lionel Salmon, Gabor Molnar, Azzedine Bousseksou
Summary: Molecular spin-crossover (SCO) compounds are a promising class of photoactive materials that exhibit efficient photoinduced phase transitions (PIPT). Through the study of the spatiotemporal dynamics of a single crystal PIPT within the thermodynamic metastability region, it was found that the PIPT occurs through the sequential activation of two switching mechanisms on sub-microsecond and millisecond timescales. The main discovery is that thermodynamic metastability has no influence on the sub-millisecond switching dynamics.
ADVANCED MATERIALS
(2022)
Article
Materials Science, Multidisciplinary
A. Meo, S. Sampan-a-pai, P. B. Visscher, R. Chepulskyy, D. Apalkov, J. Chureemart, P. Chureemart, R. W. Chantrell, R. F. L. Evans
Summary: The study investigates the spin transfer torque switching dynamics in CoFeB/MgO/CoFeB magnetic tunnel junctions using atomistic simulations based on Slonczewski's model. The results demonstrate a magnetization reversal driven by the combination of coherent and nonuniform excitation modes, affected by factors such as current density, temperature, and structural imperfections. This deeper understanding can be valuable for spin transfer torque dynamics in nanoscale devices.
Article
Chemistry, Physical
Yeonsig Nam, Francesco Montorsi, Daniel Keefer, Stefano M. Cavaletto, Jin Yong Lee, Artur Nenov, Marco Garavelli, Shaul Mukamel
Summary: In this study, we theoretically monitor the photoinduced pi pi*-> n pi* internal conversion process in 4-thiouracil (4TU) using a resonant X-ray probe tuned to the sulfur, oxygen, or nitrogen K-edge. We discuss the capabilities and limitations of the resonant technique and observe specific spectral features for sulfur and nitrogen, as well as an inaccessible transition for oxygen. Overall, this study provides a detailed understanding of the electronic excited-state dynamics and offers insights into the photophysics of thiobases.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2022)
Article
Materials Science, Characterization & Testing
Mohammed Saif Ur Rahman, Khaled Al-Wahedi, Mohamed A. Abou-Khousa
Summary: In this study, we conducted a sensitivity analysis using circular aperture probes and conventional rectangular aperture probes to evaluate their ability to detect disbond in multilayer composite structures. The results showed that the circular aperture probes have higher sensitivity and can generate higher resolution and better quality images.
JOURNAL OF NONDESTRUCTIVE EVALUATION
(2022)
Review
Chemistry, Multidisciplinary
Kuppusamy Senthil Kumar, Mario Ruben
Summary: This review covers the advances in vacuum-sublimable SCO complexes, including the design and synthesis of functional SCO complexes, on-surface SCO of thin films, and various device architectures based on sublimable SCO complexes.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Multidisciplinary Sciences
Peng-Jui Wang, Yu-Hao Pang, Sheng-Yu Huang, Jun-Tung Fang, Sui-Yuan Chang, Shin-Ru Shih, Tian-Wei Huang, Yi-Jan Chen, Chi-Kuang Sun
Summary: Low power microwave can effectively deactivate influenza type A virus through the nonthermal structure-resonant energy transfer effect. The resonant frequencies of SARS-CoV-2 virus have been identified, and they are invariant to the virus titer.
SCIENTIFIC REPORTS
(2022)
Article
Physics, Fluids & Plasmas
Federico Boni, Victor Desangles, Julien Jarrige
Summary: This article introduces a correction method for plasma sheath effects that occur when measuring electron density using a microwave resonant probe immersed in plasma. The method is developed based on evaluating the operation of the resonant probe and its interface with the plasma. Numerical simulations are used to independently develop the correction method. Experimental results demonstrate that the method significantly improves the accuracy of electron density measurements, and potential improvements are also discussed.
PLASMA SOURCES SCIENCE & TECHNOLOGY
(2023)
Article
Materials Science, Multidisciplinary
Jeremy Letang, Claudia de Melo, Charles Guillemard, Aymeric Vecchiola, Damien Rontani, Sebastien Petit-Watelot, Myoung-Woo Yoo, Thibaut Devolder, Karim Bouzehouane, Vincent Cros, Stephane Andrieu, Joo-Von Kim
Summary: This experimental study focuses on the vortex dynamics in magnetic nanocontacts based on pseudo spin valves comprising the Co2MnGe Heusler compound. By combining precise film growth and nanoindentation techniques, different types of spin-transfer induced dynamics related to different modes of the magnetic vortex configuration were observed, such as mode hopping, mode coexistence, and mode extinction, in addition to the usual gyration mode.
Article
Multidisciplinary Sciences
Debanjan Polley, Akshay Pattabi, Ashwin Rastogi, Kaushalya Jhuria, Eva Diaz, Hanuman Singh, Aristide Lemaitre, Michel Hehn, Jon Gorchon, Jeffrey Bokor
Summary: In this study, we experimentally demonstrate ultrafast spin-orbit torque-induced coherent magnetization switching dynamics in a ferromagnet and propose a unique magnetization switching mechanism that can significantly increase the writing speed of magnetic random-access memory devices.
Article
Multidisciplinary Sciences
Imara Lima Fernandes, Stefan Bluegel, Samir Lounis
Summary: This study demonstrates that chiral spin textures exhibit a magnetoresistance signature, allowing for efficient electric readout of the chirality and helicity. The linear relationship of this signature, in contrast to the quadratic dependence of conventional methods, is confirmed through simulations and experiments. This finding has important implications for exploring the rich physics of topological and chiral magnetic objects using electrical means.
NATURE COMMUNICATIONS
(2022)
Article
Astronomy & Astrophysics
Jean-Baptiste Fouvry, Chris Hamilton, Simon Rozier, Christophe Pichon
Summary: Globular clusters with a finite number of stars undergo secular evolution driven by local deflections and resonant couplings, known as non-resonant relaxation and resonant relaxation. A study comparing both relaxation theories found that they predict the correct morphology of the cluster's distribution function evolution, with non-resonant relaxation overestimating the relaxation rate by a factor of 2.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Chemistry, Physical
Chi Wang, Yuming Feng, Junjie Zhou, Guangwu Wen, Long Xia
Summary: Non-magnetic materials have great potential in microwave absorption, but analyzing the connection between performance and parameters is still challenging. This study simplifies and derives formulae, establishes criteria and fitting methods, and investigates the electromagnetic parameters for absorbing performance.
JOURNAL OF COLLOID AND INTERFACE SCIENCE
(2022)
Article
Engineering, Electrical & Electronic
Katerina Nikolaidou, Hugo M. Oliveira, Susana Cardoso, Paulo P. Freitas, Virginia Chu, Joao Pedro Conde
Summary: The study presents a novel technique for integrating multiple filters in a chip with four photodiodes, enhancing the portability and simplicity of biological detection applications. By leveraging the beneficial characteristics of different deposition techniques, precise multilayer interference filters are successfully fabricated. This integration is demonstrated through fluorescence measurements of grape fluorescence at two different wavelengths, which are used in grape maturation monitoring in the viticulture sector.
IEEE SENSORS JOURNAL
(2022)
Article
Engineering, Electrical & Electronic
Sofia Abrunhosa, Ian Gibb, Rita Macedo, Emrys Williams, Nathalie Muller, Paulo P. Freitas, Susana Cardoso
Summary: Information encoding in barcodes using magnetic-based technology allows data to be read underneath non-transparent surfaces, which has potential applications in secure labeling and recyclable packaging. By replacing traditional inductive heads with tunnel magnetoresistive sensors, the limitations of current magnetic reading heads can be overcome, enabling deeper information reading. Experimental results demonstrate that this device can read barcodes at depths of at least 1 mm and resolve structures as thin as 200 μm when in contact.
IEEE TRANSACTIONS ON MAGNETICS
(2022)
Article
Chemistry, Analytical
Lukasz Fusnik, Bartlomiej Szafraniak, Jerzy Wrona, Susana Cardoso, Paulo. P. Freitas, Piotr Wisniowski
Summary: This paper investigates the dependence of sensitivity, resistance derivative, and current on bias voltage in tunneling magnetoresistance sensors. The results show that the sensitivity does not saturate up to 1 V in sensors with voltage controlled magnetic anisotropy modification and the sensitivity asymmetry changes significantly with bias polarity. Furthermore, the contribution of current and resistance derivative to sensitivity exhibits a crossover phenomenon.
Article
Chemistry, Physical
Andrei V. Turutin, Elena A. Skryleva, Ilya V. Kubasov, Filipp O. Milovich, Alexander A. Temirov, Kirill V. Raketov, Aleksandr M. Kislyuk, Roman N. Zhukov, Boris R. Senatulin, Victor V. Kuts, Mikhail D. Malinkovich, Yuriy N. Parkhomenko, Nikolai A. Sobolev
Summary: In this article, a new technology of non-contact mapping of magnetic fields produced by the human heart muscle using miniaturized and highly sensitive magnetic field sensors is described. The technology involves the use of laminated magnetoelectric heterostructures comprising a thin piezoelectric lithium niobate single crystal and a film of magnetostrictive metglas. High quality metglas layers were deposited by magnetron sputtering and their performance was evaluated. The developed sensors achieved a high magnetoelectric coefficient, a low noise level, and an improved detection limit for AC magnetic fields.
Article
Nanoscience & Nanotechnology
Candid Reig, Maria-Dolores Cubells-Beltran, Fernando Pardo, Francisco Vegara, Jose A. Boluda, Sofia Abrunhosa, Susana Cardoso
Summary: This paper proposes a dynamic compact electrical model for bio-inspired applications of GMR based magnetic scanning sensors. The model can be directly used in most standard CMOS design platforms.
Article
Nanoscience & Nanotechnology
F. Matos, R. Macedo, P. P. Freitas, S. Cardoso
Summary: Magnetoresistive sensors, using soft magnetic free layers, are popular for small footprint magnetic field detection applications. This study explores the TMR and noise performance of in-plane MTJ sensors with magnetically saturated CoFeBTa and CoFeSiB films as free layers. The results show improved magnetoresistance of 230% in CoFeBSi with superior noise characteristics, as well as different magneto-crystalline anisotropy values compared to CoFeB/Ru/NiFe.
Article
Physics, Applied
Nikita Strelkov, Andrey Timopheev, Lea Cuchet, Salim Dounia, Clarisse Ducruet, Sergey A. Bunyaev, Gleb N. Kakazei, Jeffrey R. Childress
Summary: In magnetic tunnel junctions (MTJs), Ta nanolayers are often inserted at the interface of, or within magnetic layers to enhance the tunneling magnetoresistance. However, these modifications also lead to a reduction in magnetization and changes in magnetic properties. This paper investigates the degradation of magnetic and magneto-dynamic properties in Ta-doped Ni0.81Fe0.19 films through experiments and ab initio calculations. Both the experiment and calculations confirm the decrease in saturation magnetization parameter with increased Ta doping, and the reduction of exchange stiffness at a faster rate compared to magnetization.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2023)
Editorial Material
Materials Science, Multidisciplinary
Nikolai A. Sobolev
PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE
(2023)
Article
Chemistry, Physical
Mindaugas Andrulevicius, Evgenii Artiukh, Gunnar Suchaneck, Sitao Wang, Nikolai A. A. Sobolev, Gerald Gerlach, Asta Tamuleviciene, Brigita Abakeviciene, Sigitas Tamulevicius
Summary: X-ray photoelectron spectroscopy was used to investigate the direct synthesis of strontium and molybdenum oxide thin films by multitarget reactive magnetron sputtering. By varying the power applied to the Mo target, films with different concentrations of Mo atoms were produced. The XPS spectra revealed that both molybdenum and strontium were in the oxidized state, with Mo bonds in a lower valence state and similar Sr spectra for all samples.
Article
Physics, Applied
V. M. Andrade, N. R. Checca, V. G. de Paula, K. R. Pirota, A. L. Rossi, F. Garcia, A. Vovk, S. A. Bunyaev, G. N. Kakazei
Summary: In this study, Fe2CrAl Heusler nanoparticles with good crystallographic features were obtained using pulsed laser deposition technique. The structural, morphological, and magnetic properties of these nanoparticles were investigated, revealing slightly off-stoichiometric grains with two distinct morphologies. The magnetic behavior was found to be influenced by chemical disorder and inhomogeneity. The nanoparticles exhibited a superparamagnetic behavior and a Gilbert damping comparable to standard materials used in magnonics applications. The complex magnetostructural coupling in the nanoparticle system was discussed in comparison with the stoichiometric Fe2CrAl bulk target behavior.
JOURNAL OF APPLIED PHYSICS
(2023)
Article
Nanoscience & Nanotechnology
P. D. R. Araujo, R. Macedo, E. Paz, S. Cardoso, D. C. Leitao, P. P. Freitas
Summary: Improving the thermal resilience of magnetic tunnel junctions (MTJs) enhances their usability as sensing devices and is crucial for their operation in harsh environments. This study investigates the impact of temperature on the degradation of the magnetic reference in MgO-MTJ field sensor stacks. The results demonstrate the importance of properly designing a suitable buffer layer system and understanding the complete behavior of MTJs at different temperatures to achieve the highest resilience to high temperature environments.
Article
Nanoscience & Nanotechnology
S. Azzawi, A. Umerski, L. C. Sampaio, S. A. Bunyaev, G. N. Kakazei, D. Atkinson
Summary: Previous theory suggested that different monolayers within transition metal ferromagnet thin-films contribute different amounts to the total ferromagnetic damping. This study aimed to investigate if electronic engineering of the higher damping regions through localized doping could reduce the thin-film damping. Theoretical analysis and experimental results for sputtered Co thin-films with locally doped upper and lower surface regions with Cr were presented, showing a reduction in damping with increasing local doping up to 30% Cr, and a further decrease in damping with higher local doping potentially due to changes in the film structure. This work paves the way for the creation of low-damping magnetic thin-films.
Article
Nanoscience & Nanotechnology
Catarina Goncalves Fonseca, Vania Silverio, David Barata, Wolfgang Giese, Holger Gerhardt, Susana Cardoso, Claudio Areias Franco
Summary: The ability of endothelial cells to respond to blood flow is crucial for the formation and maintenance of a functional vascular network. However, the molecular mechanisms underlying the response to high flow conditions are still not well understood. In this study, we developed and validated a 96-wells fluidic system for high-throughput screenings under laminar high-flow conditions. Our findings demonstrate that endothelial cells in this system align along the flow direction and upregulate KLF2 and KLF4 levels in response to fluid flow-induced shear stress. Moreover, our fluidic system allows for efficient gene knock-down compatible with automated liquid handling for high-throughput screening platforms.
MICROSYSTEMS & NANOENGINEERING
(2023)
Article
Engineering, Electrical & Electronic
Diogo Miguel Caetano, Ruben Afonso, Ana Rita Soares, Joao Silva, Hanna Iva Busse, Vania Silverio, Taimur Rabuske, Goncalo N. Tavares, Jorge Ribeiro Fernandes, Susana Cardoso
Summary: In this study, an artificial neural network (ANN) is proposed for magnetic microcytometry pattern recognition and automated counting. The method is tested for detecting analytes in the range of 2-3 μm. The cytometer consists of a disposable cartridge with microfluidic channels and magnetoresistive (MR) sensors. The ANN achieves a maximum detection rate of 90%, surpassing the detection rates of other single-sensor methods reported in the literature (30%-50%).
IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT
(2023)
Article
Automation & Control Systems
Joao Silva, Diogo Miguel Caetano, Taimur Rabuske, Susana Cardoso, Moises Piedade, Jorge Ribeiro Fernandes
Summary: This article presents the design and implementation of a three-channel ASIC for signal acquisition in industrial positioning systems. The ASIC utilizes magnetic encoder scales and tunnel magneto-resistance (TMR) sensors for signal acquisition. It includes various features such as offset mitigation for Wheatstone bridge, programmable gain for instrumentation amplifier, and SAR ADC for signal digitization. The ASIC prototype is produced in XFAB 180-nm CMOS process and successfully meets the requirements of industrial applications.
IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS
(2023)