Materials In Magnetic Fields Research Articles

Ultra-compact scanning tunneling microscope enables study of superconducting materials in high magnetic fields

Instrument can capture atomic-level images of materials in magnetic fields up to 20 T and at sub 2K temperatures.

Research on extremely weak remanence measurement system

To accurately obtain the extremely weak magnetic field information of the test piece, this article first introduces the basic principles of the extremely weak residual magnetic field measurement technology. Then, an ultra-high precision magnetic shielding system has been developed, which is made of high permeability materials and equipped with a demagnetization coil system, and it can regularly eliminate the inductance of the entire shielding system. The effective shielding inner diameter of the magnetic shielding system is 0.8 m, the length is 1.6 m, and the magnetic field resolution is 0.0015 nT. This system can provide strong support for the measurement of extremely weak magnetic fields in materials and biomedical magnetic research.

Ion irradiation modulated magnetic properties of materials and its applications

Ion irradiation, a technology in which ion beams are used to irradiate materials, has high manipulation precision, short processing time, and many applications in the fields of material modification, chip manufacturing, biomedicine, energy and chemicals. Especially in magnetic material modification, customized modifications of magnetic materials can be achieved by precisely controlling the energy, dose, and direction of the ion beam. To further enhance the performances of magnetic materials and explore new magnetic devices, this study focuses on how ion irradiation precisely modulates various magnetic interactions and the analysis of its influence on the spin Hall effect and magnetic structural dynamics. Firstly, the latest research achievements are emphasized of ion irradiation regulated magnetic characteristics such as perpendicular magnetic anisotropy, exchange bias, and RKKY interaction. These regulation methods are crucial for understanding and optimizing the microstructure and properties of magnetic materials. Secondly, the significant role played by ion irradiation in regulating spin-orbit torque devices is discussed in detail. These applications demonstrate the potential of ion irradiation technology in designing high-performance magnetic storage and processing devices. Finally, the future applications of ion irradiation technology in the preparation of multifunctional magnetic sensors and magnetic media for information storage are discussed, highlighting its great enormous innovation and application potential in the field of magnetic materials.

Thermal and protonation-induced electron transfer coupled spin transition in a discrete [Fe2Co3] Prussian blue analogue.

Multi-stimuli responsive switchable molecules have garnered interest for their potential applications in the field of magnetic materials. However, the persistent challenge lies in isolating these properties within the same material. Herein, we report a discrete [Fe2Co3] pentanuclear cyanide bridged complex, [Co(L)2]3[Fe(CN)6]2·20H2O, (1) (L = (Z)-N'-(4-(trifluoromethyl)phenyl)picolinimidamide) which undergoes electron transfer coupled spin transition (ETCST) from [FeII2CoIIHSCoIII2] to [FeIII2CoII3] configurations through thermal activation and upon protonation.

Development of visual thinking strategy in augmented reality (ViTSAR) to facilitate visual literacy skills on magnetic field material

Development of visual thinking strategy in augmented reality (ViTSAR) to facilitate visual literacy skills on magnetic field material

Samarium(III) Triflate in Organic Synthesis: a Mild and Efficient Catalyst

AbstractLanthanides have shown great potential in the field of magnetic materials, telecommunications, hard‐disk drives, catalysis, medicine, agriculture, and more. Recently, lanthanide complexes have gained significant attention in cancer diagnosis and therapy because of the multifunctional chemical and magnetic activities of the lanthanide‐ion 4 f electronic configuration. Among lanthanides, samarium metal and its derivatives have been the subject of many applications in organic transformations. Various metal triflates such as Bi(OTf)3, Yb(OTf)3, In(OTf)3, Sc(OTf)3, Er(OTf)3, Ce(OTf)3, Sm(OTf)3, and others play a profound role in developing novel eco‐friendly protocols in organic synthesis with excellent efficiency and selectivity. Among lanthanide triflate, samarium(III) triflate has a remarkable contribution in synthesizing promising organic molecules as it has been shown to be moisture tolerant and a reusable Lewis catalyst under mild conditions. The present review aims to focus on different useful protocols using samarium(III) triflate as an efficient catalyst for the first time elegantly.

Micro-structural and magnetic analysis of spinel high entropy oxides synthesized by two-step pressureless sintering provides insight into high entropy ceramics

High-entropy oxides are novel materials consisting of many metallic elements of equal proportions. Hence, the complex structure of high-entropy oxides leads to interesting properties. In this work, seven single-phase high entropy oxides were synthesized by two-step pressureless sintering. According to the experimental XRD data, all samples are found in the cubic crystal structure with the Fd-3m space group. This result shows that high entropy oxides have a high possibility of phase formation. For all samples, the EDS results show that all expected elements have similar elements content. The magnetization curves show that the magnetic properties change systematically with the changes in the high-entropy stable oxide composition. The seven different samples are divided into three groups for comparison. In group 1, with the substitution of iron for zinc, Hc increased from 19 Oe to 221 Oe, while Ms changed slightly. In group 2, the substitution of zinc for nickel leads to the rapid weakening of magnetism. In group 3, with nickel replacing cobalt, Ms increased from 15.060 emu/g to 19.801 emu/g, and Hc decreased from 28 Oe to 11 Oe. The complex element composition makes high entropy materials have great development space in the field of magnetic materials. Thus, the magnetic properties of the high-entropy spinel oxides can be adjusted according to this concept.

Preparation of a Pt-Ni2P/NF catalyst for highly efficient hydrogen evolution using a magnetic field to promote Ni-Pt galvanic replacement

The noble metal Pt is an ideal catalyst for promoting the hydrogen evolution reaction (HER) during the electrolysis of water. However, Pt is also expensive and suffers from low utilization rates. In this work, a Pt-Ni 2 P/NF nanorod catalyst with a low Pt loading was synthesized under different magnetic fields, and it was found that the application of a magnetic field can increase the rate of the galvanic replacement reaction. When the magnetic field strength increases from 0 to 600 mT, the chemical reaction rate increases gradually, and the utilization rate of Pt increased by 2.3 times under 600 mT. The mechanism of the magnetic field-induced magnetohydrodynamic (MHD) effect on the galvanic replacement reaction was revealed. In a 1 M KOH solution and at a current density of 10 mA cm –2 , the overpotential of Pt-Ni 2 P/NF prepared by applying a 600 mT magnetic field was as low as 15 mV and the Tafel slope was 37 mV dec –1 , compared with values of 82 mV and 70 mV dec –1 for a specimen prepared without a magnetic field. Additionally, at an overpotential of 90 mV, the mass-based Pt activity of the former material was 12 times greater while its turnover frequency was 19 times greater. This work provides theoretical and technical knowledge expected to assist in the controllable preparation of materials in magnetic fields and the efficient utilization of metallic resources.

Students' Misconceptions: Viewed from Students' Perceptions on Magnetic Field Learning

Misconceptions are errors in connecting concepts that result in understanding new ideas and concepts in students' minds into wrong concepts. This study aims to analyze the effect of critical thinking skills on misconceptions in magnetic field material. The research method used in this study is mixed method. In this study, the sampling technique used was a simple random sampling technique to take the sample from the population. The sample used was 30 students taken randomly through a lottery, so 30 students were obtained as samples. The data collection instruments used in this study were interview sheets and questionnaires. The research design used was a sequential explanatory design. From the descriptive results of the misconceptions data, it is found that the mean of students' misconceptions is 3.59, which means that students' misconceptions are still relatively low. The descriptive results of critical thinking skills data show that the mean of critical thinking skills is 64.03, which means students' critical thinking skills are in a good category. The regression coefficient indicates an influence of critical thinking skills on misconceptions that can be seen from F_ = 28,740 with a significance/probability level of 0.001 < 0.05. It was concluded that there was an effect of critical thinking skills on misconceptions, seen from the higher the value of critical thinking skills, the lower students experiencing misconceptions.

Needs Analysis of Class XII Students of MA Raudlatul Ulum on the Development of a Recitation Program as an Interactive Learning Media on Magnetic Field Material

This study aims to analyze the needs of Class XII students of MA Raudlatul Ulum for the recitation program as an interactive learning media on magnetic field material. This research’s method is descriptive. The research subjects are class XII students of MA Raudlatul Ulum who have taken magnetic field subject. The data collection techniques are interview with 1 teacher who teaches magnetic field subject and questionnaires for 30 students. Based on the data obtained, we identified several problems that occur in the magnetic field material, including (1) the lack of time allocation in the learning process despite the magnetic field material being a broad and complex material, (2) the lack of feedback in learning, (3) less interactive and boring learning media used, (4) lack of practice questions. Referring to these problems, it is necessary to develop a recitation program as an interactive learning media on magnetic field material. This program contains practice questions accompanied by feedback on each correct or incorrect answer.

Polarizing electron spins with a superconducting flux qubit

Electron spin resonance (ESR) is a useful tool to investigate properties of materials in magnetic fields where high spin polarization of target electron spins is required in order to obtain high sensitivity. However, the smaller magnetic fields becomes, the more difficult high polarization is passively obtained by thermalization. Here, we propose to employ a superconducting flux qubit (FQ) to polarize electron spins actively. We have to overcome a large energy difference between the FQ and electron spins for efficient energy transfer among them. For this purpose, we adopt a spin-lock technique on the FQ where the Rabi frequency associated with the spin-locking can match the resonance (Larmor) one of the electron spins. We find that adding dephasing on the spins is beneficial to obtain high polarization of them, because otherwise the electron spins are trapped in dark states that cannot be coupled with the FQ. We show that our scheme can achieve high polarization of electron spins in realistic experimental conditions.

Digital Storytelling of Physics (DiS-Phy): Learning Physics from Home Through Stories

This study aims to develop a product such as “Digital storytelling of Physics (DiS-Phy)” that can be used as a physics’ educational media for distance learning (PJJ) on magnetic field material. DiS-Phy developed as a digital storytelling media which is able to combine several learning media such as writing, pictures and learning videos in one medium. The developed DiS-Phy also equipped with scientific literacy questions. DiS-Phy can be accessed on all types of distance learning devices such as smartphones, laptops and tablets that are connected to the internet. DiS-Phy including the type of research and development (Research & Development) which refers to the ASSURE model. The result of validation test shows the percentages of 91,07%, according to subject-matter expert, 93,16%, according to media expert and 87,50% according to learning expert. DiS-Phy also tested by 4 physics teachers at senior high school in Jakarta that achieved 92,57% points that make this product has been qualified as a worthy physics’ distance learning device. Also of 35 as respondents in this study shows the percentages of 87,48% points that make this product worthy to use as an educational media. Based on the results, it can be concluded that the DiS-Phy has been qualified as a worthy physics’ distance learning device for teachers and students.

The Influence of Li+ and K+ Added Cations and Annealing Temperature on the Magnetic and Dielectric Properties of Mg-Zn Ferrite.

This paper presents the results of an investigation on the magnetic and dielectric properties of Mg0.5Zn0.5Fe2O4 spinel ferrite with a 1% weight percentage of Li+ and K+ added cations. The addition of metal ions plays an important role in increasing the porosity and favors the formation of ferrite at low temperatures. The goal of this new research is to demonstrate that by selecting the type of metallic cations for addition or choosing an optimal sintering temperature, it may be possible to improve the magnetic and electrical properties of Mg-Zn ferrite. The samples were prepared using sol-gel self-combustion techniques and annealed at 1000 °C, 1100 °C, and 1200 °C. Scanning electron microscopy revealed the shape and grain size of the samples, and the phase composition was analyzed using the X-ray diffraction technique. The magnetic information, such as remanent magnetization MR, saturation magnetization MS, and coercivity HC, were extracted from the hysteresis loops of the samples. The electrical investigation was focused on the low- and high-frequency dependence of dielectric constant and dielectric losses. The results are discussed in terms of microstructural changes induced by the additions of Li+ and K+ metallic cations. Conclusions are drawn concerning the optimization of magnetic and electrical properties for the development of Mg-Zn ferrite with possible applications in the field of magnetic materials or electronics.

Teachers’ perceptions of 3D technology-integrated student worksheet on magnetic field material: A preliminary research on augmented reality in STEM learning

The change in civilization aimed at the industrial revolution 4.0 and the era of society 5.0 is a discourse in the world of education. Learning activities are a major part of education at schools, thus, they require learning devices and teaching materials updates. The development of learning resources, such as electronic student worksheets, can be used as a solution to obtain 21st-century skills. This study was aimed to analyze teacher and students’ perceptions about augmented reality-assisted worksheets with STEM approach in physics learning. The research was conducted at high schools in Lampung Province involving 139 twelfth-grade students and 16 physics teachers. The method used was the mixed-method. The research instruments used were questionnaires and telephone interviews. The results showed that teachers have not fully used augmented reality-based teaching materials STEM approach. The types of teaching materials needed by students and teachers are interactive teaching materials integrated with STEM. STEM allows students to deepen their abilities in the fields of science, technology, engineering, and mathematics, so it is necessary to develop augmented reality-assisted worksheets with STEM approach to face the challenges of the industrial revolution 4.0 and meet the competency standards in the 21st-century, namely the critical-thinking ability on magnetic field material.

Physics teachers’ perceptions and anxieties about the use of technology-integrated learning resources on magnetic field material: A preliminary research on augmented reality-integrated STEM learning

The educational world development faces the challenges of the 21st-century where technology plays an important role in learning so that technology-integrated teaching material is needed. The subjects of this study were 48 physics subject teachers in several schools in Lampung province. The research method used was a mixed method. The data was collected using questionnaires and interviews. The results of the study revealed that the teachers have never made learning resources assisted by the integration between STEM and augmented reality technology. The teachers also revealed that they were anxious that the learning resources that they will use cannot fully meet the competency standards if they are not equipped with learning technology that supports the abstract concepts learning. Thus, the teachers expected technology-assisted learning resources in which texts, images, 3D animations, and videos can be integrated. For further researchers, it is necessary to develop STEM learning resources assisted by augmented reality technology.

Wet‐chemistry approach for the synthesis of single phase ferromagnetic Co3C nanoparticle

AbstractCobalt carbides nanoparticles have great potential as novel materials in magnetic fields. However, it is difficult to synthesize single phase cobalt carbides, especially Co3C. In this paper, we propose a one‐pot wet‐chemistry approach to synthesize single phase ferromagnetic Co3C without using any alkali as nucleation solvent. The particle size of Co3C nanoparticle is about 3 nm. The magnetic properties of Co3C nanoparticles are measured at 300 K from –30 to 30 kOe. Compared with Co2C, Co3C exhibits a large saturation magnetization of 46.1 emu g–1 and a high coercivity of 1.5 kOe. Small amount of carbon and small particle size of the Co3C nanoparticle are believed to contribute to large magnetization and high coercivity. Magnetic measurements also reveal the spin glass behavior caused by the small Co3C nanoparticle at the spin freezing temperature of 43 K. This work provides a facile method to synthesize single phase Co3C nanoparticle which is applicable in magnetic field.

Probing the Magnetic Anisotropy of Co(II) Complexes Featuring Redox-Active Ligands.

Coordination complexes that possess large magnetic anisotropy (otherwise known as zero-field splitting, ZFS) have possible applications in the field of magnetic materials, including single molecule magnets (SMMs). Previous studies have explored the role of coordination number and geometry in controlling the magnetic anisotropy and SMM behavior of high-spin (S = 3/2) Co(II) complexes. Building upon these efforts, the present work examines the impact of ligand oxidation state and structural distortions on the spin states and ZFS parameters of pentacoordinate Co(II) complexes. The five complexes included in this study (1-5) have the general formula, [Co(TpPh2)(LX,Y)]n+ (X = O, S; Y = N, O; n = 0 or 1), where TpPh2 is the scorpionate ligand hydrotris(3,5-diphenyl-pyrazolyl)borate(1-) and LX,Y are bidentate dioxolene-type ligands that can access multiple oxidation states. The specific LX,Y ligands used herein are 4,6-di-tert-butyl substituted o-aminophenolate and o-aminothiophenolate (1 and 2, respectively), o-iminosemiquinonate and o-semiquinonate radicals (3 and 4, respectively), and o-iminobenzoquinone (5). Each complex exhibits a distorted trigonal bipyramidal geometry, as revealed by single-crystal X-ray diffraction. Direct current (dc) magnetic susceptibility experiments confirmed that the complexes with closed-shell ligands (1, 2, and 5) possess S = 3/2 ground states with negative D-values (easy-axis anisotropy) of -41, -78, and -30 cm-1, respectively. For 3 and 4, antiferromagnetic coupling between the Co(II) center and o-(imino)semiquinonate radical ligand results in S = 1 ground states that likewise exhibit very large and negative anisotropy (-100 > D > -140 cm-1). Notably, ZFS was measured directly for each complex using far-infrared magnetic spectroscopy (FIRMS). In combination with high-frequency and -field electron paramagnetic resonance (HFEPR) studies, these techniques provided precise spin-Hamiltonian parameters for complexes 1, 2, and 5. Multireference ab initio calculations, using the CASSCF/NEVPT2 approach, indicate that the strongly negative anisotropies of these Co(II) complexes arise primarily from distortions in the equatorial plane due to constrictions imposed by the TpPh2 ligand. This effect is further amplified by cobalt(II)-radical exchange interactions in 3 and 4.

Smart Tools for Smart Applications: New Insights into Inorganic Magnetic Systems and Materials

This Special Issue, consisting of four reviews and three research articles, presents some of the recent advances and future perspectives in the field of magnetic materials and systems, which are designed to meet some of our current challenges.

Machine-learning-guided discovery of the gigantic magnetocaloric effect in HoB2 near the hydrogen liquefaction temperature

Magnetic refrigeration exploits the magnetocaloric effect, which is the entropy change upon the application and removal of magnetic fields in materials, providing an alternate path for refrigeration other than conventional gas cycles. While intensive research has uncovered a vast number of magnetic materials that exhibit a large magnetocaloric effect, these properties remain unknown for a substantial number of compounds. To explore new functional materials in this unknown space, machine learning is used as a guide for selecting materials that could exhibit a large magnetocaloric effect. By this approach, HoB2 is singled out and synthesized, and its magnetocaloric properties are evaluated, leading to the experimental discovery of a gigantic magnetic entropy change of 40.1 J kg−1 K−1 (0.35 J cm−3 K−1) for a field change of 5 T in the vicinity of a ferromagnetic second-order phase transition with a Curie temperature of 15 K. This is the highest value reported so far, to the best of our knowledge, near the hydrogen liquefaction temperature; thus, HoB2 is a highly suitable material for hydrogen liquefaction and low-temperature magnetic cooling applications.

Electrical properties of Ca3–xSmxCo4O9+δ ceramics prepared under magnetic field**Project supported by the National Natural Science Foundation of China (Grant No. 51302055).

We fabricate Sm-doped Ca3Co4O9+δ (CCO) bulk materials in magnetic field during both processes of chemical synthesis and cold pressing. The structure and electrical performance of the samples are investigated. With the increasing Sm concentration, the electrical conductivity 1/ρ decreases and the Seebeck coefficient α increases. As a result, the power factor (PF = α2/ρ) is raised slightly. After applying magnetic field, the extent of texture, grain size and density of all the bulk materials are improved obviously, thereby an enhanced electrical conductivity can be gained. Additionally, the degeneracy of Co4+ state in the CoO2 layer of CCO is also increased as the magnetic field is used in the preparing process, which results in an enhanced α. The Ca2.85Sm0.15Co4O9+δ prepared in magnetic field shows the largest power factor (0.20 mW⋅m−1⋅K−2 at 1073 K).