Materials In Magnetic Fields Research Articles

Field-induced magnetic incommensurability in multiferroicNi3TeO6

Using single crystal neutron scattering we show that the magnetic structure Ni$_3$TeO$_6$ at fields above 8.6 T along the $c$ axis changes from a commensurate collinear antiferromagnetic structure with spins along c and ordering vector $Q_C$= (0 0 1.5), to a conical spiral with propagation vector $Q_{IC}$= (0 0 1.5$\pm\delta$),$\delta\sim$0.18, having a significant spin component in the ($a$,$b$) plane. We determine the phase diagram of this material in magnetic fields up to 10.5 T along $c$ and show the phase transition between the low field and conical spiral phases is of first order by observing a discontinuous jump of the ordering vector. $Q_{IC}$ is found to drift both as function of magnetic field and temperature. Preliminary inelastic neutron scattering reveals that the spin wave gap in zero field has minima exactly at $Q_{IC}$ and a gap of about 1.1 meV consisting with a cross-over around 8.6 T. Our findings excludes the possibility of the inverse Dzyaloshinskii-Moriya interaction as a cause for the giant magneto-electric coupling earlier observed in this material and advocates for the symmetric exchangestriction as the origin of this effect.

Magnetic core loss behavior at high fields in magnetic materials

Magnetic core loss behavior at high fields in magnetic materials

Developing CAI-PBL with DDD-E model on magnetic fields concept

Technological developments are widely used in various fields including education. Computers is a product of technological development where in the world of education is used as a tool or media in learning. Today has been a lot of computer-based learning media but still focused on the delivery of material only. While the research will be developed is the making of CAI were in it integrated a model of learning to deliver the material. The purpose of this research is to develop a product of CAI through problem-based learning on magnetic field material. This research uses DDD-E (Decide, Design, Develop and Evaluate) development method. At the phase of the decision has analysed the needs associated with the manufacture of CAI-PBL. Furthermore, based on the results of needs analysis, CAI-PBL is designed and developed by researchers. Then validated at the evaluate stage by three validators (two physicists, and one media expert). It can be concluded that the development of CAI-PBL can have the potential to solve problem-solving skills.

ANALISIS KETERAMPILAN BERPIKIR TINGKAT TINGGI DALAM MENYELESAIKAN SOAL UN FISIKA SMA PADA MATERI MEDAN MAGNET SISWA KELAS XII DI SMA MUHAMMADIYAH 3 JEMBER

This study aims to describe the high-level thinking skills of students in solving high school physics UN questions on magnetic field material. This research is a type of descriptive research with research subjects namely students of class XII MIPA Muhammadiyah 3 Jember High School. The data collection technique used was a written test consisting of five UN questions of magnetic field material that was modified in the form of descriptive questions. Based on the results of the study, the average percentage of high-level thinking skills of students in completing the National Examination (UN) questions on high school physics in magnetic field material is as follows: the analysis stage is 33.13%, the evaluation stage is 29.77%, and the creative stage is 21.05%. The analysis phase has a large percentage so that it shows students are able to decipher information (known and asked) as well as steps to solve the problems given. While the creation stage has a low percentage so that it shows students are not accustomed to re-checking answers according to known data with coherent steps.

Modelling of sensored speed control of BLDC motor using MATLAB/SIMULINK

<span style="font-size: 9pt; font-family: 'Times New Roman','serif'; mso-bidi-font-style: italic; mso-fareast-font-family: 'Times New Roman'; mso-ansi-language: EN-US; mso-fareast-language: EN-US; mso-bidi-language: AR-SA;">Recent developments in the field of magnetic materials and power electronics, along with the availability of cheap powerful processors, have increased the adoption of brushless direct current (BLDC) motors for various applications, such as in home appliances as well as in automotive, aerospace, and medical industries. The wide adoption of this motor is due to its many advantages over other types of motors, such as high efficiency, high dynamic response, long operating life, relatively quiet operation, and higher speed ranges. This paper presents a simulation of digital sensor control of permanent magnet BLDC motor speed using the MATLAB/SIMULINK environment. A closed loop speed control was developed, and different tests were conducted to evaluate the validity of the control algorithms. Results confirm the satisfactory operation of the proposed control algorithms.</span>

Implementation e-learning as a formative assessment to explore mastery concept’s student on magnetic field material

E-learning is the tool for helping teachers as well as students to evaluate the physics learning. The current study aims to determine the effect of using e-learning as a form of formative assessment in the students’ mastery concepts in the topic magnetic material. This study is conducted using the mixed method of the explanatory design method. The qualitative data is as supporting of quantitative data. The research subjects were students of class XII IPA 2 Pujon NU Islamic High Schools as many as 31 students. The mastery of concept data is taken from the pre-test and post-test and strengthened by the results of formative assessment. Acquisition of mastery concept values are based on the analysis obtaining that the average pre-test and post-test values increased for each indicator of achievement of competency. The increase of the value from 33 points to 54 points that has a maximum score of 100 points. In the formative assessment, the highest score of the first meeting is 40 points, the second meeting is 45 points and the third meeting is 25 points.

Thermal Hall signatures of non-Kitaev spin liquids in honeycomb Kitaev materials

Motivated by the recent surge of field-driven phenomena discussed for Kitaev materials, in particular the experimental observation of a finite thermal Hall effect and theoretical proposals for the emergence of additional spin liquid phases beyond the conventional Kitaev spin liquid, we develop a theoretical understanding of the thermal Hall effect in honeycomb Kitaev materials in magnetic fields. Our focus is on gapless U(1) spin liquids with a spinon Fermi surface, which have been shown to arise as field-induced phases. We demonstrate that in the presence of symmetry-allowed, second-neighbor Dzyaloshinskii-Moriya interactions these spin liquids give rise to a finite, non-quantized, thermal Hall conductance in a magnetic field. The microscopic origin of this thermal Hall effect can be traced back to an interplay of Dzyaloshinskii-Moriya interaction and Zeeman coupling, which generates an internal U(1) gauge flux that twists the motion of the emergent spinons. We argue that such a non-quantized thermal Hall effect is a generic response in Kitaev models for a range of couplings.

Microstructural Effects on the Surface of Materials in Magnetic Fields

Changes in metallic and nonmetallic materials under the influence of a pulsed magnetic field are studied, using the method of target metallography. It is shown that the structural changes are at the minimum detectable level of the microscopic method with peak gains. It is established that local variation in structure and degradation in the sharpness of separate surface areas of the samples independent of errors in focusing is a general structure change in the action of a magnetic field. The stresses of the third kind are considered to be possible reasons for the change in structure.

Effect of Cr, C, B and Mo substitutions on the structure and magnetic properties of Zr-Co Rare-Earth-free magnetic alloy

Acquiring new permanent magnets without Rare-Earths is a new challenge in the field of magnetic materials and Co-rich Co-Zr alloys seem to be a solution to be pursued. The microalloying effects of different elements on the structure and stabilization of hard magnetic Zr2Co11 phase of Zr-Co alloy have been analysed in the past and it was shown that the Zr2Co11 non-cubic high anisotropy structure can be stabilized by the partial substitution of Co in the ZrCo alloy with elements with high atomic radius. In the present work, we made substitutions of up to 5% alloying elements such as Mo, C, B, Cr in order to highlight how the element with the small / large atomic radius stabilize the nano-hard magnetic phase. The structural and magnetic properties of the new Zr18Co77Cr3X2 (X = C, B, Mo) prepared bulk alloys have been analysed and related to those of the original Zr13Co87.

Investigation on lanthanum substitution in magnetic and structural properties of group IV elements

Concerning to the profuse applications in the field of magnetic materials, group IV elements have received a significant attention owing to its chemical stability and high electrical resistivity. In this investigation, appropriation of rare earth (Lanthanum) has been substituted in NiFe2O4 and CuFe2O4, which has a large ionic radii and the spinel lattice could prominently influence the structural, optical and magnetic properties of ferrite crystals. These nanocrystals are prepared via co-precipitation route. The structural property of the samples were characterized by XRD, as the La doped NiFe2O4 had a small crystallite size when compared to CuFe2O4, doped La inhibits the grain growth of the NiFe2O4 in efficient manner compared with that of CuFe2O4 nanocrystal. FTIR shows two absorption bands in tetrahedral and octahedral sites. UV–visible spectra depicts the absorbance of lanthanum doped NiFe2O4 and CuFe2O4 nanoparticles with the band-gap ranging from 2.1 to 2.3 eV. The morphology was studied using TEM. The magnetic parameters have been studied using Vibrating sample magnetometer. The effects of the change in magnetic structures on the surface of the nanocrystals and the contribution from single ion anisotropy of lanthanum ions present in the crystal lattice were found using Vibrating sample magnetometer.

The 9th Seminar on Magnetic Materials (9th SMM)

PrefaceWe are very pleased to present the Proceedings of the 9th Seminar on Magnetic Materials 2015 held in Palembang, South Sumatera, Indonesia on October 19th – 21st, 2015. The seminar aimed to be a platform on academic exchange for materials scientists, especially in magnetic materials through invited talks and distinguish lectures series. In total, we received 40 manuscripts and all of them have been reviewed by the reviewers. Those manuscripts are covering 7 topics on magnetic materials and applications meeting: magnetism and characterizations; magnetic materials applications on clean energy materials, transportation and vehicles; aerospace and defense; health care; environment and oil refining; electronics; and natural resources of magnetic materials.Among those manuscripts, after a very intensive reviewing process, 3 papers have been accepted by the Physica B’s Editors and then published in Physica B: Condensed Matter 2017, Vol. 526 of Elsevier and the other 30 manuscripts are published in the Journal of Physics Conference Series 2018, Institute of Physics (IoP).We are really honored as the selected seminar papers were published in the regular issues of high impact factor international journals, i.e. Physica B of Elsevier. This achievement is showing the level and quality of the regional/international meeting in Indonesia, organised by the Center for Science and Technology of Advanced Materials (PSTBM) - National Nuclear Energy Agency (BATAN) Indonesia in collaboration with the Faculty of Mathematics and Natural Sciences (FMIPA) - University of Sriwijaya.Here, we are delighted to acknowledge the incredible support from the Ministry of Industry of the Republic Indonesia (Kemenperin), the Indonesian Institute of Sciences (LIPI), the University of Indonesia (UI), the Institute Technology of Sepuluh Nopember (ITS) Surabaya, the University of Gadjah Mada (UGM) Yogyakarta, the University of Padjadjaran (Unpad) Bandung, the Institute Technology of Bandung (ITB), the Agency of the Assessment and Application of Technology (BPPT).We hope that the present proceedings provide the valuable information to the readers in the field of magnetic materials and its applications.Dr. Poedji Loekitowati Hariani (Unsri) and Edy Giri Rachman Putra, Ph.D (BATAN)Chairpersons of the 9th Seminar on Magnetic Materials

Sub-\xc5ngstrom electric field measurements on a universal detector in a scanning transmission electron microscope

Scanning transmission electron microscopy (STEM) excels in accessing atomic-scale structure and chemistry. Enhancing our ability to directly image the functionalities of local features in materials has become one of the most important topics in the future development of STEM. Recently, differential phase contrast (DPC) imaging has been utilized to map the internal electric and magnetic fields in materials from nanoscale features such as p–n junctions, skyrmions, and even from individual atoms. Here, we use an ultra-low noise SCMOS detector in as the diffraction plane camera to collect four-dimensional (4D) datasets. The high angular resolution, efficient high-SNR acquisition, and modifiability of the camera allow it to function as a universal detector, where STEM imaging configurations, such as DPC, bright field, annular bright field, and annular dark field can all be reconstructed from a single 4D dataset. By examining a distorted perovskite, DyScO3, which possesses projected lattice spacings as small as 0.83 Å, we demonstrate DPC spatial resolution almost reaching the information limit of a 100 keV electron beam. In addition, the perovskite has ordered O-coordinations with alternating octahedral tilts, which can be quantitatively measured with single degree accuracy by taking advantage of DPC’s sensitivity to light atoms. The results, acquired on a standard Ronchigram camera as opposed to a specialized DPC detector, open up new opportunities to understand and design functional materials and devices that involve lattice and charge coupling at nano- and atomic-scales.

The anhysteretic polarisation of ferroelectrics

Measurement and calculation of anhysteretic curves is a well-established method in the field of magnetic materials and is applied to ferroelectric materials here. The anhysteretic curve is linked to a stable equilibrium state in the domain structure, and ignores dissipative effects related to mechanisms such as domain wall pinning. In this study, an experimental method for characterising the anhysteretic behaviour of ferroelectrics is presented, which is subsequently used to determine the anhysteretic polarisation response of polycrystalline barium titanate and a doped lead zirconate titanate composition at room temperature. Various external parameters, such as electric field, stress, and temperature, can significantly affect ferroelectric behaviour. Ferroelectric hysteresis curves can assess the importance of such effects but cannot distinguish their contribution on the different intrinsic and extrinsic mechanisms involved in ferroelectric behaviour. In this work, the influence of compressive stress on the anhysteretic polarisation is measured and discussed. The comparison of the polarization loop to the anhysteretic curve under compressive stress elucidates the effects on the stable equilibrium domain configuration and dynamic effects associated to dissipation.

Unexpected Competition between Antiferromagnetic and Ferromagnetic States in Hf2MnRu5B2: Predicted and Realized.

Materials "design" is increasingly gaining importance in the solid-state materials community in general and in the field of magnetic materials in particular. Density functional theory (DFT) predicted the competition between ferromagnetic (FM) and antiferromagnetic (AFM) ground states in a ruthenium-rich Ti3Co5B2-type boride (Hf2MnRu5B2) for the first time. Vienna ab initio simulation package (VASP) total energy calculations indicated that the FM model was marginally more stable than one of the AFM models (AFM1), indicating very weak interactions between magnetic 1D Mn chains that can be easily perturbated by external means (magnetic field or composition). The predicted phase was then synthesized by arc-melting and characterized as Hf2Mn1-xRu5+xB2 (x = 0.27). Vibrating-scanning magnetometry shows an AFM ground state with TN ≈ 20 K under low magnetic field (0.005 T). At moderate-to-higher fields, AFM ordering vanishes while FM ordering emerges with a Curie temperature of 115 K. These experimental outcomes confirm the weak nature of the interchain interactions, as predicted by DFT calculations.

Iron-titania-ilmenite triplex composites from natural ilmenite: Facile large scale preparation and electromagnetic properties

Iron-titania-ilmenite triplex composite particles (TCPs) are prepared through a facile calcination induced fractional crystallization route for the first time with natural ilmenite as the starting material. The effects of the calcination condition on the composition, structure and properties of the composites were studied. It is found that the stepwise calcination in oxidizing (first) and reducing (second) environments is the key point to realize the high efficient fractional crystallization and reduction of ilmenite. Contrast experiments with different calcination conditions have also been carried out, and the results reveal that it is possible to tailor the composition and structure of the composite particles by control over the duration of the reduction process. The electromagnetic properties of the TCPs are studied and the results demonstrate that they present ferromagnetic and microwave absorbing properties depended on the processing condition and the composition of the composites, and may have some promising applications in the fields of magnetic materials and microwave absorbers. This work provides a new strategy for the economic and large scale fabrication of multicomponent electromagnetic composites with tailored composition and property from low-cost starting materials, which may be extended to the preparation of other metal-oxide composites or other compounds.

Student understanding of electric and magnetic fields in materials

We discuss the clusters of resources that emerge when upper-division students write about electromagnetic fields in linear materials. The data analyzed for this paper come from students' written tests in an upper-division electricity and magnetism course. We examine how these clusters change with time and context. The evidence shows that students benefit from activating resources related to the internal structure of the atom when thinking about electric fields and their effect on materials. We argue that facilitating activation of certain resources by the instructor in the classroom can affect the plasticity of those resources in the student, making them more solid and easily activated. We find that the wording of the questions posed to students affects which resources are activated, and that students often fill in resources to link known phenomena to phenomena described by the question when lacking detailed mental models.

Preparation of high performance soft magnetic alloy Fe-4Si-0.8P by metal injection molding

Fe-4Si-0.8P soft magnetic alloy was prepared by metal injection molding (MIM). Ferrophosphorus liquid phase sintering promoted densification and enhanced magnetic properties. The sample with nearly full density, the saturation induction of 1.59T, maximum permeability of 2467, coercive force of 130A/m and resistivity of 81.2 μΩ·cm was obtained at 1300°C for 4h. Competitive properties contributed toward achieving low magnetic losses. Therefore, MIM Fe-4Si-0.8P can be widely used in the field of magnetic materials.

Anomalous room temperature magnetorheological behavior of colloidal graphene nanogels

Weak magnetism is known to exist in graphene systems, yet, as of now, it remains unharnessed for bulk scale applications. Weak ferromagnetic response from chemically exfoliated graphene samples has been employed to harness appreciable magnetorheological effects via the use of novel graphene nanogels. Chemically exfoliated graphene samples have been synthesized and ferromagnetic response has been registered (in tune with scarce reports in literature). Characterizations reveal that presence of magnetic impurities would be unable to yield magnetic moments as obtained and hence the response is innate to the vacancy and defects in the graphenic structure. Polymer based nanogels with infused graphene nanoplatelets has been synthesized and the colloidal gel phase enables harnessing of magnetorheology from such weak moment systems. Strong magnetorheological response is obtained from the colloidal gel phase due to the compact texture which aids in fibrillation of the nanoplatelets. Largely enhanced magnetoviscosity and yield stress have been observed from the gels in similitude to conventional magnetorheological nanocolloids. The presence of dispersed phase with platelet morphology as well as surface lubrication behavior of graphene has been found responsible for certain anomalous behavior such as magnetic shear thickening in the gels which has been explained based on order to disorder transitions under field influence. Transient response of the gels show good modulation caliber in field actuated viscous control as well as minute magnetoviscous hysteresis. The present colloids show novel promise in use of graphene as potential magnetic material in magnetic field governed actuation, control and tuning MEMS/NEMS and allied devices.

Magnetic field simulation of a thermal conductivity measurement instrument for magnetorheological fluid

Technological advancements in thermal systems demand an innovative heat dissipation technology. Magnetorheological (MR) fluid has a huge potential to solve the problem. However, characterising thermal conductivity of the materials in magnetic fields required tailored instruments. This paper presents a concept design of the MR fluids thermal conductivity measurement instrument. The developed instrument was designed to be able to measure thermal conductivity in both parallel and perpendicular orientations with magnetic field. Magnetic fields distribution of the proposed concept design was analysed using finite element method for magnetics. Design modification then conducted to improve the magnetic fields strength. Findings of this study showed that gap thickness played a significant factor in determining the optimal design. Simulated magnetic fields strength at both parallel and perpendicular orientations were found identical, yet varied in distributions.

Soft magnetic ε-Fe3N: Synthesis, characterization and magnetic properties

ε-Fe3N can be flexibly synthesized via a sol-gel route by using ethylenediamine as the nitrogen source, and the role of ethylenediamine can be demonstrated by adjusting the molar ratio of ethanediamine to acetone. Excellent magnetic properties (72.35 emu/g) and coercivity are obtained at the optimized condition, showing the potential applications in magnetic material field. In addition, the probable formation mechanism of iron nitride is investigated in this article, supported by XRD patterns and etc, which has important effect on the further research of the iron nitride via a sol-gel route.