Engineering Commons^™

Electromagnetic Theory And Applications, Nicholas Madamopoulos, George Kliros

Open Educational Resources

This book intends to provide both the fundamentals of Electromagnetics but also some practical applications of the concepts covered. Having taught electromagnetics for several years, the authors feel that many times the field of electromagnetics comes as “old” and often times students do not appreciate the concepts and their importance in everyday applications. The authors intend to accompany the EM concepts with life applications. Hence, students may see the direct impact of the knowledge they acquire through the study of the field of electromagnetics and better appreciate the field.

Vector Magneto-Optical Generalized Ellipsometry On Magnetic Slanted Columnar Heterostructured Thin Films, Chad Briley

Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research

Modern material growth techniques allow for nano-engineering highly complex three dimensionally nanostructured materials. These nano-engineered materials possess highly anisotropic physical properties that are significantly different from that of their bulk counterparts. The magnetization properties of nano-engineered materials can be modified through a close range interaction known as magnetic exchange. These materials are referred to as magnetic exchange-coupled materials. Exchange-coupled magnetic materials are composite magnetic materials where the magnetization of one material is influenced by the magnetization state of the neighboring materials.

The author describes the creation of a representative sample set of exchange-coupled nanoengineered magnetic materials. These materials are created …

Imaging Of Membrane Concentration Polarization By Nacl Using 23na Nuclear Magnetic Resonance, Masoumeh Zargar, Ryuta Ujihara, Sarah J. Vogt, Johannes S. Vrouwenvelder, Einar O. Fridjonsson, Michael L. Johns

Research outputs 2014 to 2021

Forward osmosis (FO) and reverse osmosis (RO) membrane processes differ in their driving forces: osmotic pressure versus hydraulic pressure. Concentration polarization (CP) can adversely affect both performance and lifetime in such membrane systems. In order to mitigate against CP, the extent and severity of it need to be predicted more accurately through advanced online monitoring methodologies. Whilst a variety of monitoring techniques have been used to study the CP mechanism, there is still a pressing need to develop and apply non-invasive, in situ techniques able to produce quantitative, spatially resolved measurements of heterogeneous solute concentration in, and adjacent to, the …

Ferroelectrically Tunable Magnetism In Bifeo3/Batio3 Heterostructure Revealed By The First-Principles Calculations, Wenxuan Wang, Wei Sun, Guangbiao Zhang, Fengzhu Ren, Yuanxu Wang, Caiyin You, Zhenxiang Cheng

Australian Institute for Innovative Materials - Papers

© 2020 The perovskite oxide interface has attracted extensive attention as a platform for achieving strong coupling between ferroelectricity and magnetism. In this work, robust control of magnetoelectric (ME) coupling in the BiFeO3/BaTiO3 (BFO/BTO) heterostructure (HS) was revealed by using the first-principles calculation. Switching of the ferroelectric polarization of BTO induce large ME effect with significant changes on the magnetic ordering and easy magnetization axis, making up for the weak ME coupling effect of single-phase multiferroic BFO. In addition, the Dzyaloshinskii-Moriya interaction (DMI) and the exchange coupling constants J for the BFO part of the HSs are simultaneously manipulated by …

Tuning The Magnetic Ground State Of Ce1−Xybxrhin5 By Yb Valence Fluctuations, S. Jang, N. Pouse, T. Keiber, Benjamin White, S. M. Dissler, J. W. Lynn, J. C. Collini, M. Janoschek, F. Bridges, M. Brian Maple

All Faculty Scholarship for the College of the Sciences

We characterize the properties of Ce_1−xYb_xRhIn₅ single crystals with 0 ⩽ x ⩽ 1 using measurements of powder x-ray diffraction, energy dispersive x-ray spectroscopy, electrical resistivity, magnetic susceptibility, specific heat, x-ray absorption near edge structure (XANES), and neutron diffraction. The Yb valence v_Yb, calculated from the magnetic susceptibility and measured using XANES, decreases from 3+ at x = 0 to ∼2.1+ at x_act = 0.2, where x_act is the measured Yb concentration. A transition from incommensurate to commensurate antiferromagnetism is observed in neutron diffraction measurements …

Suppression Of Magnetism In Ba5Alir2O11: Interplay Of Hund's Coupling, Molecular Orbitals, And Spin-Orbit Interaction, Sergey V. Streltsov, Gang Cao, Daniel I. Khomskii

Center for Advanced Materials Faculty Publications

The electronic and magnetic properties of Ba₅AlIr₂O₁₁ containing Ir-Ir dimers are investigated using the generalized gradient approximation (GGA) and GGA + spin-orbit coupling (SOC) calculations. We found that the strong suppression of the magnetic moment in this compound recently found by Terzic et al. [Phys. Rev. B 91, 235147 (2015)] is not due to charge ordering but is related to the joint effect of the spin-orbit interaction and strong covalency, resulting in the formation of metal-metal bonds. They conspire and act against the intraatomic Hund's rule exchange interaction to reduce total magnetic moment of the …

Fabrication And Study Of The Structure And Magnetism Of Rare-Earth Free Nanoclusters, Bhaskar Das

Department of Physics and Astronomy: Dissertations, Theses, and Student Research

No abstract provided.

Manipulating Coupling State And Magnetism Of Mn-Doped Zno Nanocrystals By Changing The Coordination Environment Of Mn Via Hydrogen Annealing, Yan Cheng, W Li, Weichang Hao, Huaizhe Xu, Zhongfei Xu, Li Rong Zheng, Jing Zhang, S X. Dou, Tianmin Wang

Australian Institute for Innovative Materials - Papers

Mn-doped ZnO nanocrystals are synthesized by a wet chemical route and treated in H2/Ar atmosphere with different H2/Ar ratios. It is found that hydrogen annealing could change the coordination environment of Mn in ZnO lattice and manipulate the magnetic properties of Mn-doped ZnO. Mn ions initially enter into interstitial sites and a Mn3+O6 octahedral coordination is produced in the prepared Mn-doped ZnO sample, in which the nearest neighbor Mn3+ and O2 ions could form a Mn3+-O2--Mn3+ complex. After H2 annealing, interstitial Mn ions can substitute for Zn to generate the Mn2+O4 tetrahedral coordination in the nanocrystals, in which neighboring Mn2+ …

Enhanced Magnetism In Field-Cooled [Ni80fe20/Mn]3 Multilayers Studied Using Polarized Neutron Reflectometry, W Uilhoorn, S J. Callori, David L. Cortie, Hui-Chia Su, Y Khaydukov, Ko-Wei Lin, Frank Klose

Australian Institute for Innovative Materials - Papers

Here, the interfacial magnetic coupling in an exchange biased [Ni80Fe20/Mn]3 multilayer system has been studied using polarized neutron re ectometry. Previous results on this system indicate the importance of the coupling between the Fe-Mn and Ni-Mn orbitals at the layer interfaces. Magnetic depth profiles of the multilayer were measured at low temperatures under field-cooled and zero-field-cooled conditions. While no definitive interfacial state was found, a magnetic moment enhancement of roughly 20-30% in the applied field direction was observed throughout the bulk of the NiFe layers in the field-cooled state as compared to the zero-field-cooled measurements. The origin of this enhancement …

Weak Magnetic Field Accelerates Chromate Removal By Zero-Valent Iron, Pian Feng, Xiaohong Guan, Yuankui Sun, Wonyong Choi, Hejie Qin, Jianmin Wang, Junlian Qiao, Lina Li

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Weak magnetic field (WMF) was employed to improve the removal of Cr(VI) by zero-valent iron (ZVI) for the first time. The removal rate of Cr(VI) was elevated by a factor of 1.12-5.89 due to the application of a WMF, and the WMF-induced improvement was more remarkable at higher Cr(VI) concentration and higher pH. Fe2+ was not detected until Cr(VI) was exhausted, and there was a positive correlation between the WMF-induced promotion factor of Cr(VI) removal rate and that of Fe²⁺ release rate in the absence of Cr(VI) at pH 4.0-5.5. These phenomena imply that ZVI corrosion with Fe^{2+ …}

Properties Of Exchange Coupled All-Garnet Magneto-Optic Thin Film Multilayer Structures, Mohammed Nur-E-Alam, Mikhail Vasilev, Viacheslav A. Kotov, Dmitry Balabanov, Ilya Akimov, Kamal Alameh

Research outputs 2014 to 2021

The effects of exchange coupling on magnetic switching properties of all-garnet multilayer thin film structures are investigated. All-garnet structures are fabricated by sandwiching a magneto-soft material of composition type Bi_1.8Lu_1.2Fe_3.6Al_1.4O₁₂ or Bi₃Fe₅O₁₂:Dy₂O₃ in between two magneto-hard garnet material layers of composition type Bi₂Dy₁Fe₄Ga₁O₁₂ or Bi₂Dy₁Fe₄Ga₁O₁₂:Bi₁₂O₃. The fabricated RF magnetron sputtered exchange-coupled all-garnet multilayers demonstrate a very attractive combination of …

Comparison Of Magnetic Resonance Imaging-Compatible Optical Detectors For In-Magnet Tissue Spectroscopy: Photodiodes Versus Silicon Photomultipliers, Fadi El-Ghussein, Shudong Jiang, Brian W. Pogue, Keith D. Paulsen, Brian W. Pogue

Dartmouth Scholarship

Tissue spectroscopy inside the magnetic resonance imaging (MRI) system adds a significant value by measuring fast vascular hemoglobin responses or completing spectroscopic identification of diagnostically relevant molecules. Advances in this type of spectroscopy instrumentation have largely focused on fiber coupling into and out of the MRI; however, nonmagnetic detectors can now be placed inside the scanner with signal amplification performed remotely to the high field environment for optimized light detection. In this study, the two possible detector options, such as silicon photodiodes (PD) and silicon photomultipliers (SiPM), were systematically examined for dynamic range and wavelength performance. Results show that PDs …

Sr Measurements Of The Magnetism Of Sr3fe2o7, W A. Macfarlane, D Peets, T Buck, K H. Chow, David L. Cortie, A Jain, C Pomerantz, C B. L Tschense, D Wang, B Keimer

Australian Institute for Innovative Materials - Papers

We present a preliminary report of zero and transverse field ¿SR measurements in a high quality single crystal of fully oxygenated Sr3Fe2O7[1], the insulating 3d magnetic analogue of the well studied Sr3Ru2O7, in its charge-disproportionated state, through the magnetic transition to the incommensurate phase at TN ¿ 115 K. A very broad distribution of static fields below Tn yields a large (2/3) missing fraction. Rapidly damped zero field oscillations indicate a large internal field at the muon, estimated to be 0.46 T at 0 K. In the paramagnetic state, we find two muon precession frequencies at 0.25 T applied field, …

Magnetism And Magnetocaloric Effect Of Mn0.98fe0.02coge, Q Y. Ren, W D. Hutchison, Jianli Wang, S Munoz Perez, J M. Cadogan, S J. Campbell

Australian Institute for Innovative Materials - Papers

The crystallographic and magnetic properties of Mn0.98Fe0.02CoGe have been investigated by X-ray diffraction, dc magnetization and neutron diffraction over the temperature range 20-450 K. The temperature dependence of the phase fractions of the orthorhombic and hexagonal phases is described well by a Gaussian distribution. The Mn0.98Fe0.02CoGe sample exhibits a first-order magneto-structural transition centred at TMS ∼ 297 K of FWHM ∼37 K with a magnetic entropy change of −ΔSM = 24(1) J kg−1 K−1 for ΔB = 0-5 T. Neutron diffraction indicates a ferromagnetic orthorhombic structure below TMS with only the Mn carrying magnetic moment (3.98(6) µB) at 20 K. …

Element-Specific Depth Profile Of Magnetism And Stoichiometry At The La0.67sr0.33mno3/Bifeo3 Interface, Joel Bertinshaw, S Bruck, D Lott, H Fritzsche, Y Khaydukov, O Soltwedel, T Keller, E Goering, P Audehm, David L. Cortie, Wayne D. Hutchison, Q Ramasse, M Arredondo, R Maran, Vinayaka Nagarajan, Frank Klose, Clemens Ulrich

Australian Institute for Innovative Materials - Papers

Depth-sensitive magnetic, structural, and chemical characterization is important in the understanding and optimization of physical phenomena emerging at the interfaces of transition metal oxide heterostructures. In a simultaneous approach we have used polarized neutron and resonant x-ray reflectometry to determine the magnetic profile across atomically sharp interfaces of ferromagnetic La0.67Sr0.33MnO3/multiferroic BiFeO3 bilayers with subnanometer resolution. In particular, the x-ray resonant magnetic reflectivity measurements at the Fe and Mn resonance edges allowed us to determine the element-specific depth profile of the ferromagnetic moments in both the La0.67Sr0.33MnO3 and BiFeO3 layers. Our measurements indicate a magnetically diluted interface layer within the La0.67Sr0.33MnO3 …

Ti Substitution For Mn In Mncoge - The Magnetism Of Mn0.9ti0.1coge, Jianli Wang, P Shamba, W D. Hutchinson, M F. Md Din, J C. Debnath, M Avdeev, R Zeng, S J. Kennedy, S J. Campbell, S X. Dou

Australian Institute for Innovative Materials - Papers

Bulk magnetization measurements (5-320 K; 0-8T) reveal that below room temperature Mn0.9Ti0.1CoGe exhibits two magnetic phase transitions at ~178 K and ~280 K. Neutron diffraction measurements (3-350K) confirm that the transition at ~178K is due to the structural change from the low-temperature orthorhombic TiNiSi-type structure to the higher temperature hexagonal Ni2In-type structure while the transition at ~280K originates from the transition from feromagnetism to paramagnetism.

Magnetism And The Magnetocaloric Effect In Prmn1. 6fe0. 4ge2, W D. Hutchison, Jianli Wang, S J. Campbell

Australian Institute for Innovative Materials - Papers

The magnetic and magnetocaloric properties of PrMn1.6Fe0.4Ge2around the ferromagnetic transitions T C inter ~ 230 K and T C Pr ~ 30 K have been investigated by magnetisation, 57Fe Mössbauer spectroscopy and electron paramagnetic resonance (EPR) measurements over the temperature range 5–300 K. The broad peaks in magnetic entropy around TC inter (intralayer antiferromagnetism of the Mn sublattice to canted ferromagnetism) and TC Pr (onset of ferromagnetic order of Pr sublattice in addition to ferromagnetically ordered Mn sublattice) are typical of second order transitions with maximum entropy values of -ΔS M ~ 2.0 J/kg K and -ΔS M ~ 2.2 …

Substitution Of Y For Pr In Prmn2ge2-The Magnetism Of Pr0.8y0.2mn2ge2, Jianli Wang, S J. Campbell, M Hofmann, S J. Kennedy, M Avdeev, M F. Md Din, R Zeng, Z X. Cheng, S X. Dou

Australian Institute for Innovative Materials - Papers

Pr0.8Y0.2Mn2 Ge 2 is found to exhibit four magnetic transitions on decreasing the temperature from the paramagnetic region: (i) paramagnetism to intralayer antiferromagnetism (AFl) at TN intra; (ii) AFl to canted ferromagnetism (Fmc) at TC inter; (iii) Fmc to conical magnetic ordering of the Mn sublattice (Fmi) at Tcc; and (iv) Fmi(Mn) to Fmi(Mn) + F(Pr) at TC Pr. These changes in magnetic structure are discussed in terms of changes in the Mn-Mn separation distances caused by the unit cell contraction and by electronic effects due to replacement of 20% of Pr with Y.

Anisotropy Of Crystal Growth Mechanisms, Dielectricity, And Magnetism Of Multiferroic Bi2femno6 Thin Films, P Liu, Z X. Cheng, Y Du, L Y. Feng, H Fang, Xiaolin Wang, S X. Dou

Australian Institute for Innovative Materials - Papers

Epitaxial Bi2FeMnO6 (BFMO) thin films deposited on various Nb:SrTiO3 substrates show that the lattice parameters are very sensitive to epitaxial strains. Compressive and tensile strains are induced to the in-plane lattice constants of the (100) and (111) oriented films, respectively, while that of the (110) oriented thin film stay unstrained. The thin films also exhibit a strongly anisotropic growth habit depending on the substrate. Spiral growth, such as in the (100) BFMO film, is unique in samples prepared by pulsed laser deposition. Extrinsic dielectric constants at low frequencies are attributed to oxygen vacancies via the Maxwell-Wagner effect. All the samples …

Magnetism And Magnetic Structures Of Prmn2ge2-Xsix, Jianli Wang, S J. Campbell, M Hofmann, S J. Kennedy, R Zeng, M Md Din, S X. Dou, A Arulraj, N Stusser

Australian Institute for Innovative Materials - Papers

The structural and magnetic properties of seven PrMn2Ge2-xSix compounds with Si concentrations in the range x = 0.0-2.0 have been investigated by x-ray diffraction, magnetic (5- 350 K), differential scanning calorimetry (300-500 K) and neutron diffraction (3-480 K) measurements. Replacement of Ge by Si leads to a contraction of the unit cell and significant modifications to the magnetic states-a crossover from ferromagnetism at room temperature for Ge-rich compounds to antiferromagnetism for Si-rich compounds. The compositional dependence of the room temperature lattice parameters exhibits non-linear behaviour around x = 1.2, reflecting the presence of magnetovolume effects. Re-entrant ferromagnetism has been observed …

Thermodynamics Of Magnetic Multilayers, Tathagata Mukherjee

Department of Physics and Astronomy: Dissertations, Theses, and Student Research

Our interest in thermodynamics of magnetic thin film heterostructure began by exploring the possibility to use magnetic nanostructures in the search for optimized magnetocaloric materials for potential room temperature refrigeration. In the present thesis magnetic thin film heterostructures are experimentally realized by Molecular Beam Epitaxy (MBE) and Pulsed Laser Deposition (PLD). Co/Cr and Fe/Cr superlattices were fabricated using mean-field theoretical concepts as guiding principles. The potential of artificial antiferromagnets for near room-temperature refrigeration is explored. Magnetocaloric properties are deduced from measurements of the temperature and field dependence of the magnetization of our samples. The effects of intra-plane and inter-plane exchange …

Spin Wave Scattering And Interface Magnetism In Superconducting-Ferromagnet-Superconducting Hybrid Structures, Gustavo A. Alvarez, Xiaolin Wang, T Puzzer, Germanas Peleckis, S. X. Dou

Faculty of Engineering - Papers (Archive)

In this work we report on interlayer spin-polarized transport studies carried out on YBa₂Cu₃O_7-δ/La_2/3Sr_1/3MnO₃/YBa₂Cu₃O_7-δ thin film multilayers. Anisotropic YBa₂Cu₃O_7-δ high-temperature superconductors (YBCO) and the manganite La_2/3Sr_1/3MnO₃ (LSMO) are layered metallic systems where the c-axis interlayer current transport occurs via sequential tunneling of charge carriers. The temperature dependence of the resistance R(T) for different applied fields shows that these heterostructures are clearly influenced by both the insulator-to-metal …

Superconductivity And Local-Moment Magnetism In Eu(Fe0.89co0.11) 2as2, Shuai Jiang, Hui Xing, Guofang Xuan, Zhi Ren, Cao Wang, Zhu-An Xu, Guanghan Cao

Faculty of Engineering - Papers (Archive)

We report the measurements of resistivity and magnetization under magnetic fields parallel and perpendicular to the basal plane, respectively, on a cobalt-doped Eu(Fe0.89Co0.11)2As2 single crystal. We observed a resistivity drop at Tc˜21K , which shifts toward lower temperatures under external fields, suggesting a superconducting transition. The upper critical fields near Tc show large anisotropy, in contrast with those of other “122” FeAs-based superconductors. Low-field magnetic susceptibility data also show evidence of superconductivity below 21 K. Instead of the expected zero resistance below Tc , however, a resistivity re-entrance appears at 17 K under zero field, coincident with the magnetic ordering …

Magnetic Order In Yba₂Cu₃O₆₊ₓ Superconductors, Herbert A. Mook, Pengcheng Dai, Stephen M. Hayden, Arno Hiess, Jeffrey W. Lynn, Seunghun Lee, Fatih Dogan

Materials Science and Engineering Faculty Research & Creative Works

Polarized and unpolarized neutron diffraction has been used to search for magnetic order in YBa₂Cu₃O_6+x superconductors. Most of the measurements were made on a high quality crystal of YBa₂CU₃O_6.6. It is shown that this crystal has highly ordered ortho-II chain order, and a sharp superconducting transition. Inelastic scattering measurements display a very clean spin-gap and pseudogap with any intensity at 10 meV being 50 times smaller than the resonance intensity. The crystal shows a complicated magnetic order that appears to have three components. A magnetic phase is found at …

Observation Of Changes In The Atomic And Electronic Structure Of Single-Crystal Yba₂Cu₃O₆.₆ Accompanying Bromination, Lamine M. Dieng, Yasuhiro Inamura, Trevor A. Tyson, Mark C. Croft, Fatih Dogan, C. Y. Kim, Joseph C. Woicik, James M. Grow

Materials Science and Engineering Faculty Research & Creative Works

To ascertain the role of bromination in the recovery of superconductivity in underdoped YBa₂Cu₃O_6+y (YBCO), we have performed polarized multiple-edge x-ray-absorption fine structure (XAFS) measurements on normal (y~0.6) and brominated (Br/Cu~1/30, y~0.6) single crystals with superconducting transitions at 63 and 89 K, respectively. The brominated sample becomes strongly heterogeneous on an atomic length scale. Approximately one-third of YBCO is locally decomposed yet incorporated as a well-ordered "host" lattice as nanoscale regions. The decomposed phase consists of heavily distorted domains with an order not following that of the "host" lattice. Structurally, these domains are fragments of …

Observation Of Magnetic Moments In The Superconducting State Of Yba₂Cu₃O₆.₆, Herbert A. Mook, Pengcheng Dai, Fatih Dogan

Materials Science and Engineering Faculty Research & Creative Works

Neutron scattering measurements for YBa₂Cu₃O_6.6 have identified small magnetic moments that increase in strength as the temperature is reduced below T* and further increase below T_c. An analysis of the data shows the moments are antiferromagnetic between the Cu-O planes with a correlation length of longer than 195 Å in the a-b plane and about 35 Å along the c axis. The origin of the moments is unknown, and their properties are discusssed both in terms of Cu spin magnetism and orbital bond currents.

Direct Current High-Pressure Glow Discharges, Robert H. Stark, Karl H. Schoenbach

Bioelectrics Publications

Stabilization and control of a high-pressure glow discharge by means of a microhollow cathode discharge has been demonstrated. The microhollow cathode discharge, which is sustained between two closely spaced electrodes with openings of approximately 100 μm diam, serves as plasma cathode for the high-pressure glow. Small variations in the microhollow cathode discharge voltage generate large variations in the microhollow cathode discharge current and consequently in the glow discharge current. In this mode of operation the electrical characteristic of this system of coupled discharges resembles that of a vacuum triode. Using the microhollow cathode discharge as plasma cathode it was possible …