Bulletin of the American Physical Society
APS March Meeting 2021
Volume 66, Number 1
Monday–Friday, March 15–19, 2021; Virtual; Time Zone: Central Daylight Time, USA
Session R40: Magnetic Structures: Nanowires, Nanoparticles & Additive ManufacturingFocus Live
|
Hide Abstracts |
Sponsoring Units: GMAG DMP Chair: Dhritiman Bhattacharya, Virginia Commonwealth University |
Thursday, March 18, 2021 8:00AM - 8:36AM Live |
R40.00001: Reversal mechanisms in cylindrical magnetic nanowires Invited Speaker: Bethanie Joyce Hills Stadler Magnetic nanowires (MNWs) can be engineered using composition and shape, and by modulating both |
Thursday, March 18, 2021 8:36AM - 8:48AM Live |
R40.00002: Strain Mediated Magneto-Electric Effects in coaxial nanofibers of Y or W type hexagonal ferrites and ferroelectric PZT or Barium Titanate Ying Liu, Wei Zhang, Gopalan Srinivasan This work is on the synthesis of coaxial nanofibers of Y- or W-type hexagonal ferrites and barium titanate (BTO) or lead zirconate titanate (PZT) by electrospinning, assembly of the fibers into films in a magnetic field and measurements of strengths of magnetoelectric (ME) interactions. Electrospinning was carried out in electric fields of ~ 2 kV/cm by dispensing sol-gels of the ferrites and ferroelectrics through a dual chamber needle. Core-shell fibers with an average diameter of 0.5 to 1.5 micron were prepared. Fibers annealed at 700-900 C were found to be free of impurity phases by x-ray diffraction. The core-shell structure was confirmed by electron- and scanning probe microscopy. The nanofibers showed ferroelectric and ferromagnetic order parameters expected for bulk materials. ME coupling strength was measured for films assembled in magnetic fields. Fibers with PZT and W-type hexaferrites showed a higher ME voltage coefficient (MEVC) than for PZT-Y-type ferrites with a maximum value of 20 mV/cm Oe. Films with Y-type ferrite and BTO showed a maximum MEVC of 16.4 mV/cm Oe. The hexaferrite-ferroelectric coaxial nanofibers are of interest for use as miniature sensors of magnetic fields. |
Thursday, March 18, 2021 8:48AM - 9:00AM Live |
R40.00003: Spin Distributions in Fe3O4@CoxZn1-xFe2O4 Core-Shell Nanoparticles Corisa Kons, Supun B Attanayake, Kathryn Lynn Krycka, Julie Borchers, Raja Das, Manh-Huong Phan, Hariharan Srikanth, Dario Arena Magnetic nanoparticles (MNPs) are suitable for biomedical hyperthermia treatments; for this application important material parameters include saturation magnetization and anisotropy. Low anisotropy leads to undesirable spin canting and recent efforts to avoid this include synthesizing core / shell MNPs with magnetically hard and soft materials. In this work, CS MNPS consisting of an Fe3O4 core and a Zn-doped CoFe2O4 shell are studied with polarization analyzed small angle neutron scattering (SANS) in order to explore magnetic properties and spin coupling as a function of doping concentration. The higher anisotropy of Co-ferrite allows for a greater range of anisotropy variations and spin canting effects when doped with Zn than would be possible with Fe3O4 alone. Magnetometry of all MNPs reveal the existence of a Verwey transition (Tv) while SANS shows changes in magnetic ordering above and below this temperature. Below Tv the MNPs see both perpendicular and parallel magnetic ordering at low fields that diminishes with increasing temperature, disappears in the vicinity of Tv, and weakly reorders at higher temperatures while no change in spin ordering is seen at higher fields above or below Tv. Perpendicular magnetic moments confirm the presence of spin canting within the MNPs. |
Thursday, March 18, 2021 9:00AM - 9:12AM Live |
R40.00004: Disorder Dissipation in Superparamagnetic Nanoparticle Chains Assembled in a Rotating Magnetic Field Hans Robinson, Zhixing He Chaining of superparamagnetic particles is well understood in two limits: Finite-temperature assembly of magnetic nanoparticles in a static magnetic field, and far-from equilibrium assembly of larger magnetic beads in a rotating field. Here, we study chaining of magnetic nanoparticles in a rotating field, achieving a combined regime where self-assembly occurs both away from thermal equilibrium and at finite temperatures. Theories applicable to both limits qualitatively describe the observed chain length distribution, except that chains are significantly shorter than in either limit. Most notably, if the chains are incubated in the rotating field for tens of minutes, the disorder initially present in the chains gradually dissipates. The disorder dissipation can be sped up by increasing the solution ionic strength or the particle concentration, both of which increase the velocity of chain assembly. We therefore conclude that the chain order is not only improved through thermal fluctuations acting on individual chains, but also by way of the assembly, during which chains continually grow and fall apart, providing an influx of energy sufficient to liberate chains from kinetic traps so they can evolve toward a higher degree of order. |
Thursday, March 18, 2021 9:12AM - 9:24AM Live |
R40.00005: Exploiting Spin Interaction in Magnetic Nanoparticles to Improve Magnetic Thermosensitivity and AC Field Response Adam Biacchi, Thinh Bui, Eduardo De Lima Correa, Cindi L Dennis, Solomon Isaac Woods, Angela Hight Walker Remote 3D magnetic thermometry is an emerging application of colloidal magnetic nanoparticles (MNPs). The technique employs MNPs to measure and image temperature remotely with high spatial resolution throughout a 3D volume. This metrology is based on the soft magnetic behavior found in many nanoscale ferrimagnets, which yields a strong and temperature-dependent collective response to applied AC magnetic fields. Here, we report MNPs specifically designed for remote 3D thermometry. A series of shape- and size-controlled colloidal MNPs based on ferrites were synthesized via solution routes and their AC magnetization response was determined as a function of temperature, frequency, and field amplitude. Further, we exploit compositional doping of transition metals and exchange coupling between core-shell heterostructures as means of generating improved magnetization and thermosensitivity from spin interaction within the MNPs. Extensive structural characterization was performed to better understand the underlying factors influencing the magnetic response, which revealed correlations between the nanoscale atomic structure of the particles and their magnetic performance. These studies constiute an important step in our effort to tune the response dynamics of MNPs under AC driving fields. |
Thursday, March 18, 2021 9:24AM - 9:36AM Live |
R40.00006: Magnetic Microparticle Transport on Disk Arrays in Time-Varying Magnetic Fields: Simulation and Experiment Gregory Vieira, Chris Hoang, Eliza Howard Magnetic microspheres are fluid-borne magnetic particles, often made of iron oxide encased in polystyrene. These particles are designed for bioseparation of cells, proteins, DNA, and RNA, whereas they can be specifically bound to these targets allowing for field gradients to separate the particles from a mixture. Recent work has been done in the development of surface-based transport schemes and means of applying magnetic forces, showing promise for use in on-chip devices. We investigate particle motion on one such architecture, arrays of permalloy disks, aided by application of time-varying magnetic fields. I will discuss both long-range (100s of micrometer) and short range (<10 micrometer) microsphere transport on disk arrays. Furthermore, I will show comparison between computer models which simulate transport and observed behavior. Our model predicts limitations to particle speed due to phase-slipping motion, describes how transport depends on particle size, and suggests a means for estimating low-field magnetic susceptibilities of individual particles. |
Thursday, March 18, 2021 9:36AM - 9:48AM Live |
R40.00007: Magnetic Neutron Scattering of Nanoparticles: Failure of The Superspin Model Evelyn SINAGA, Laura G Vivas, Eddwi Hasdeo, Philipp Bender, Andreas Michels It is known that beyond a certain size magnetic nanoparticles exhibit a nonuniform internal spin structure.This feature, which is of relevance for many problems of practical interest (e.g., biomedical imaging and drug delivery), is commonly ignored when it comes to the analysis of magnetic neutron scattering data on nanoparticle ensembles.By means of numerical micromagnetic computations we study the transition from single-domain to multi-domain behavior in nanoparticles and its implications for the ensuing elastic magnetic small-angle neutron scattering (SANS) cross-section.Above the critical single-domain size we find that the magnetic SANS cross-section and the related correlation function cannot be described anymore with the uniform particle model, resulting e.g. in deviations from well-known Guinier Law. Independent of particle concentration, we identify a clear signature for the occurrence of a vortex-like spin structure at remanence [1]. The micromagnetic approach to magnetic SANS offers greater flexibility than the structural-model-based superspin approach and allows one to access the contributions of the individual Fourier components to the cross-section and to obtain a deeper understanding of magnetic SANS. |
Thursday, March 18, 2021 9:48AM - 10:00AM Live |
R40.00008: Emergence of Magnetic Field-Modulated Negative Magnetoresistance in Manganese Phosphide Nanorod Thin Films Baleeswaraiah Muchharla, Richa Pokharel Madhogaria, Chang-Ming Hung, Anh Tuan Duong, Huy Thanh Pham, Sarath Witanachchi, Manh-Huong Phan Manganese phosphide (MnP) is a complex magnetic material with multiple exotic magnetic phases. Here we report the temperature dependent charge and spin transport properties of a MnP nanorod thin film over a wide temperature range (2 K < T < 350 K). The MnP nanorod thin films of ~100 nm thickness were grown on Si substrates at 500 °C using molecular beam epitaxy (MBE). The temperature dependent resistivity (ρ) data for the MnP film exhibit a metallic behavior (dρ/dT > 0) over the entire measured temperature window. However, negative magnetoresistance (MR) up to 12 % is observed for the MnP film at low temperatures (< 100 K) under the application of high magnetic fields up to 8 T. With reference to the MnP single crystal whose stable helical (screw) phase develops below 47 K, the MR(H) dependence reveals a high field-manipulated CONE + FAN phase coexistence in the MnP film. This important finding pinpoints a correlation between the transport and magnetism in helical magnetic systems like MnP for perspective spintronics applications. |
Thursday, March 18, 2021 10:00AM - 10:12AM Live |
R40.00009: Effect of Demagnetization Technique on Remanence Measurements in Metallic Ferromagnets Jennifer Freedberg, E. Dan Dahlberg Measurements of the remagnetization and demagnetization remanences of metallic ferromagnets were made using four different paths to zero magnetization (AC, DC, and thermal demagnetization) [1]. Parametric plots of these quantities, commonly known as Henkel plots, were compared to Wohlfarth’s model for noninteracting particulate ferromagnets [2]. Like the expected results for individual particles, our results show that the path to net zero magnetization strongly affects subsequent measurements. Although similar to Wohlfarth’s model in this regard, the overall adherence to his model was poor. However, many qualitative similarities between our data and models including magnetic interactions were found [3]. |
Thursday, March 18, 2021 10:12AM - 10:24AM Live |
R40.00010: Structure and Magnetism of Fe/Fe3C Nanoparticles in Carbon Spheres Harutyun Gyulasaryan, Elisavet Papadopoulou, Nikolaos Tetos, Gayane Chilingaryan, Marina Spasova, Michael Farle, Aram Manukyan, Eirini Myrovali, Makis Angelakeris, Kevin Castillo, Oscar Bernal, Armen Kocharian Iron-cementite (Fe/Fe3C) nanoparticles in carbon spheres were synthesized by a solid-phase pyrolysis of iron phthalocyanine. The morphology, sizes and composition of the synthesized nanocomposite were studied by high-resolution transmission and scanning transmission electron microscopes (HRTEM, STEM), Mossbauer spectroscopy, X-ray diffraction and extended X-ray absorption fine structure (EXAFS). The M-T dependence shows a significant increase of magnetization at temperatures slightly below 10 K. Apparently, such behavior at low temperatures can be associated with the magnetic properties of the carbon matrix. The heating efficiency of samples under study was evaluated by forming aqueous solutions of 10 mg/mL and exposing them in AC magnetic field 375 kHz/60 mT. Fe-content is a determinant of heating efficiency quantification as expressed by the Specific Loss Power Index. Thus, we surmise that with facile synthetic steps, currently underway, SLP value may enhance even further and render such nanoparticles biomedically exploitable. |
Thursday, March 18, 2021 10:24AM - 10:36AM Live |
R40.00011: Altering Magnetic Properties of Iron Filament PLA Using Magnetic Field Assisted Additive Manufacturing
Lauren Henderson1, Tanjina N. Ahmed2, Camila Belduque3, Jitendra Tate2,3, Maggie Chen2,4 and Wilhelmus J. Geerts1,2
1. Depart Lauren Henderson, Tanjina Ahmed, Maria Camila Belduque, Jitendra S. Tate, Maggie Chen, Wilhelmus J Geerts Use of soft magnetic materials are on the rise, and the search for more environmentally friendly, yet practical, materials remains prevalent. In this research, the magnetic properties of 3D samples printed in a magnetic field were explored, referred to as Magnetic Field Assisted Additive Manufacturing (MFAAM), where a magnetic field is applied to a material during printing. MFAAM has shown strong effects on the magnetic properties of hard magnetic 3D printed composites, increasing the materials energy product and remanence, yielding stronger permanent magnets. Here we explore a 3D print field's effects on the properties of eco-friendly iron filled Proto-pasta, i.e. its susceptibility and hysteresis. These factors are important for transformers in reducing the amount of energy lost during each cycle. Samples printed in zero field, a field parallel to the long axis, and a field perpendicular to the long axis were examined using a Vibrating Sample Magnetometer (VSM). Through varying field angle measurements, the data revealed that in the presence of a printed magnetic field, the sample’s susceptibility increased by a factor of two, suggesting MFAAM can increase the functionality of soft magnetic materials. |
Thursday, March 18, 2021 10:36AM - 10:48AM Live |
R40.00012: Demonstration of additively manufactured NdFeB PPS Halbach magnets to generate variable magnetic fields for neutron reflectometry Tej Lamichhane, Timothy R Charlton, Brian Andrews, Arjun Pathak, M. Doucet, Valeria Lauter, John Katsaras, Brian Post, Mariappan Parans Paranthaman Halbach arrays are the most efficient closed structures for generating directed magnetic fields and gradients, which are widely applied in various electrical machines. However, Halbach arrays require multiple magnet pieces that are exactly alike and are oriented in a specific pattern, which makes them challenging to traditionally manufacture. We utilized the fused deposition modeling-based Big Area Additive Manufacturing technology to print customized, compensated concentric Halbach array discs, using polyphenylene sulfide -bonded NdFeB permanent magnets for polarized neutron reflectometry. The discs could generate a 0 ≤ B ≤ 0.30 T field and demonstrated 90% polarization conservation of a traversed neutron beam. Such a setup will be widely useful for generating additional magnetic contrast and for phase recovery in polarized neutron reflectometry, for magnetic multi-layers, heterostructures, biological membranes, and interfaces. |
Thursday, March 18, 2021 10:48AM - 11:00AM Live |
R40.00013: Torque measurements of Strontium Ferrite/PA12 composite filaments and 3D printed samples printed in a magnetic field Tanjina Nasreen Ahmed, Maria Camila Belduque, Jitendra S. Tate, Wilhelmus J. Geerts Magnetic composites are being investigated for use in permanent magnets, transformers, electrical machines, and magnetic shielding. Materials are manufactured through additive processes such as Fused Filament Fabrication to allow for rapid prototyping and highly complex designs compared to magnetic composites manufactured through conventional methods. In this study, magnetic filaments are made by adding 5wt% and 26wt% of SrO(Fe2O3)6 powders into Nylon-12 using a co-rotating twin-screw extruder. Additionally, we apply an external magnetic field during the 3D printing process. This allows the magnetic particles to be oriented in a well-defined direction resulting in the realization of magnetic structures with complex well-defined easy axis and/or magnetic dipole distribution functions that vary across a mesoscopic scale. The magnetic torque curves of the filaments and of 3D printed samples under exposure of a field are determined with a biaxial VSM. The hysteresis curves indicate that manufactured filaments have a flow-induced anisotropy with an easy plane perpendicular to the filament’s cylindrical axis, indicating a wire texture. The 3D printed material also shows field-induced and shape anisotropies. |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700