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Full-Text Articles in Physics

Synergistic Interactions Of H2 And N2 With Molten Gallium In The Presence Of Plasma, Maria L. Carreon, Daniel F. Jaramillo-Cabanzo, Indira Chaudhuri, Madhu Menon, Mahendra K. Sunkara Dec 2017

Synergistic Interactions Of H2 And N2 With Molten Gallium In The Presence Of Plasma, Maria L. Carreon, Daniel F. Jaramillo-Cabanzo, Indira Chaudhuri, Madhu Menon, Mahendra K. Sunkara

Physics and Astronomy Faculty Publications

The present study examines the interaction of hydrogen and nitrogen plasmas with gallium in an effort to gain insights into the mechanisms behind the synergetic effect of plasma and a catalytic metal. Absorption/desorption experiments were performed, accompanied by theoretical-computational calculations. Experiments were carried out in a plasma-enhanced, Ga-packed, batch reactor and entailed monitoring the change in pressure at different temperatures. The results indicated a rapid adsorption/dissolution of the gas into the molten metal when gallium was exposed to plasma, even at a low temperature of 100 °C. The experimental observations, when hydrogen was used, indicate that gallium acts as a …


Magnetization Reversal In Ferromagnetic Spirals Via Domain Wall Motion, Ryan D. Schumm, Andrew Kunz Nov 2016

Magnetization Reversal In Ferromagnetic Spirals Via Domain Wall Motion, Ryan D. Schumm, Andrew Kunz

Physics Faculty Research and Publications

Domain wall dynamics have been investigated in a variety of ferromagnetic nanostructures for potential applications in logic, sensing, and recording. We present a combination of analytic and simulated results describing the reliable field driven motion of a domain wall through the arms of a ferromagnetic spiral nanowire. The spiral geometry is capable of taking advantage of the benefits of both straight and circular wires. Measurements of the in-plane components of the spirals' magnetization can be used to determine the angular location of the domain wall, impacting the magnetoresistive applications dependent on the domain wall location. The spirals' magnetization components are …


Magnetoresistance Characteristics In Individual Fe3O4 Single Crystal Nanowire, K. M. Reddy, Nitin P. Padture, Alex Punnoose, Charles Hanna May 2015

Magnetoresistance Characteristics In Individual Fe3O4 Single Crystal Nanowire, K. M. Reddy, Nitin P. Padture, Alex Punnoose, Charles Hanna

Physics Faculty Publications and Presentations

We report on the magnetoresistance (MR) and electron transport measurements observed on asingle crystal magnetite nanowire prepared using a hydrothermal synthesis method. High-resolution electron microscopy revealed the single crystal magnetite nanowires with 80–120 nm thickness and up to 8 μm in length. Magnetic measurements showed the typical Verwey transition around 120 K with a 100 Oe room temperature coercivity and 45 emu/g saturationmagnetization, which are comparable to bulk magnetite. Electrical resistance measurements in 5-300 K temperature range were performed by scanning gate voltage and varying appliedmagnetic field. Electrical resistivity of the nanowire was found to be around 5 × …


Heterojunction Metal-Oxide-Metal Au-Fe3O4-Au Single Nanowire Device For Spintronics, K. M. Reddy, Nitin P. Padture, Alex Punnoose, Charles Hanna May 2015

Heterojunction Metal-Oxide-Metal Au-Fe3O4-Au Single Nanowire Device For Spintronics, K. M. Reddy, Nitin P. Padture, Alex Punnoose, Charles Hanna

Physics Faculty Publications and Presentations

In this report, we present the synthesis of heterojunction magnetite nanowires in alumina template and describe magnetic and electrical properties from a single nanowire device for spintronics applications. Heterojunction Au-Fe-Au nanowire arrays were electrodeposited in porous aluminum oxide templates, and an extensive and controlled heat treatment process converted Fe segment to nanocrystalline cubic magnetite phase with well-defined Au-Fe3O4 interfaces as confirmed by the transmission electron microscopy. Magnetic measurements revealed Verwey transition shoulder around 120 K and a room temperature coercive field of 90 Oe. Current–voltage (I-V) characteristics of a single Au-Fe3O4-Au nanowire have …


Reproducible Nanostructure Fabrication Using Atomic Force Microscopy Indentation With Minimal Tip Damage, Seunghee Jeon, Bongwoo Ryu, Wonho Jhe, Zheong G. Khim, Byung I. Kim Jan 2014

Reproducible Nanostructure Fabrication Using Atomic Force Microscopy Indentation With Minimal Tip Damage, Seunghee Jeon, Bongwoo Ryu, Wonho Jhe, Zheong G. Khim, Byung I. Kim

Physics Faculty Publications and Presentations

A uniform pattern of quantum dots and nanowires were reproducibly fabricated by creating holes in a two-layer structure using atomic force microscopy (AFM) indentation, dry-etching of polymer resists, and metal deposition through the indentation holes. The two-layer structure was created by depositing a thin gold layer onto a polymethyl methacrylate (PMMA) layer on a silicon substrate. The indentation depth was set so that the AFM tip penetrated the thin gold layer without the tip contacting the silicon substrate. This two-layer indentation was used to create a pattern of holes in the thin gold layer. Then, the PMMA was exposed to …


Frequency Multiplication In Nanowires, Marius Ghita, Ed Godshalk, Gary Goncher, Raj Solanki Oct 2011

Frequency Multiplication In Nanowires, Marius Ghita, Ed Godshalk, Gary Goncher, Raj Solanki

Physics Faculty Publications and Presentations

Frequency multiplication in silicon and ZnO nanowire based Schottky and p-n diodes has been demonstrated at fundamental frequencies of 70 MHz and 500 MHz. Our motivation for using nanowires contacted at their tips was to minimize the spreading resistance and boundary capacitance in order to produce higher cut-off frequencies and conversion efficiencies compared to planar diodes. The data presented here are limited to the lower GHz range by the frequency response of the experimental apparatus. However, by employing microwave waveguides and higher fundamental source frequencies, it should be possible to reach much higher output frequencies with nanowire-based diodes.


Synthesis And Characterization Of N- And P- Doped Tin Oxide Nanowires, Hoang Tran, Shankar B. Rananavare Aug 2011

Synthesis And Characterization Of N- And P- Doped Tin Oxide Nanowires, Hoang Tran, Shankar B. Rananavare

Chemistry Faculty Publications and Presentations

Bulk-scale synthetic methods for preparing doped tin oxide (SnO2) nanowires (NWs) are presented. n-and p-doping is achieved through insertion of Antimony and Lithium in tin oxide lattice, respectively. We also present a comparison of the structural and optical properties of SnO2 nanoparticles (NPs), and SnO2 NWs. Both n-type and p- type NWs display a characteristic red shift in their photoluminescence (PL) spectra. Surface plasmons observed in these systems imply high carrier concentrations. These corrosion resistant materials are useful in fabricating ultra-sensitive gas detectors and transparent electronics.


Bis Photobase Generator, Hoang Tran, Shankar B. Rananavare Aug 2011

Bis Photobase Generator, Hoang Tran, Shankar B. Rananavare

Chemistry Faculty Publications and Presentations

The extension of 193nm technology is desirable due to the magnitude of past investments. Since “optical” advancements are increasingly difficult, there is a strong demand for more sophisticated “smart” resists to increase pattern density. Many studies have proven double pattering can be used for the extension of 193nm lithography. In this study, a new class of two stage photo base generators will be introduced along with the synthetic procedure and molecular characterization. The characterizations for exposure study by NMR have shown typical characteristics to stage decomposition under the exposure of 254nm light as well as promising pitch division. GCMS was …


Dynamical Conductivity At The Dirty Superconductor-Metal Quantum Phase Transition, Adrian Del Maestro, Bernd Rosenow, Jose A. Hoyos, Thomas Vojta Oct 2010

Dynamical Conductivity At The Dirty Superconductor-Metal Quantum Phase Transition, Adrian Del Maestro, Bernd Rosenow, Jose A. Hoyos, Thomas Vojta

Physics Faculty Research & Creative Works

We study the transport properties of ultrathin disordered nanowires in the neighborhood of the superconductor-metal quantum phase transition. To this end we combine numerical calculations with analytical strong-disorder renormalization group results. The quantum critical conductivity at zero temperature diverges logarithmically as a function of frequency. In the metallic phase, it obeys activated scaling associated with an infinite-randomness quantum critical point. We extend the scaling theory to higher dimensions and discuss implications for experiments.


Fabrication And Magnetic Properties Of Fe Nanostructures In Anodic Alumina Membrane, J H. Lim, W S. Chae, H O. Lee, L Malkinski, S G. Min, J B. Wiley, J H. Jun, S H. Lee, J S. Jung Jan 2010

Fabrication And Magnetic Properties Of Fe Nanostructures In Anodic Alumina Membrane, J H. Lim, W S. Chae, H O. Lee, L Malkinski, S G. Min, J B. Wiley, J H. Jun, S H. Lee, J S. Jung

Physics Faculty Publications

Several Fe nanostructures with different lengths, diameters, and separations of the constituting magnetic components have been synthesized using anodized alumina membranes (AAMs) to understand the influence of these parameters on their magnetic properties. Fe nanostructures with high crystallinity and (110) orientation were synthesized by electrodeposition at room temperature in regular AAMs and mild-hard AAM (Mi-Ha AAM). Fe nanostructures with different aspect ratios (1:1, 1:10, and 1:75) in the form of nanodots, nanorods, or nanowires were synthesized in regular AAMs with the 100 nm interpore distance. Mi-Ha AAMs with two different pore sizes (70 and 120 nm) and 250 nm interpore …


Voltage-Induced Switching With Magnetoresistance Signature In Magnetic Nano-Filaments, Andrei Sokolov, Renat F. Sabirianov, Ildar F. Sabiryanov, Bernard Doudin Jan 2009

Voltage-Induced Switching With Magnetoresistance Signature In Magnetic Nano-Filaments, Andrei Sokolov, Renat F. Sabirianov, Ildar F. Sabiryanov, Bernard Doudin

Physics Faculty Publications

Large hysteretic resistance changes are reported on sub-100 nm diameter metallic nanowires including thin dielectric junctions. Bi-stable 50% switching in a double junction geometry is modeled in terms of an occupation-driven metal–insulator transition in one of the two junctions, using the generalized Poisson expressions of Oka and Nagaosa (2005 Phys. Rev. Lett. 95 266403). It illustrates how a band bending scheme can be generalized for strongly correlated electron systems. The magnetic constituents of the nanowires provide a magnetoresistive signature of the two resistance states, confirming our model and enabling a four states device application.


Field Induced Domain Wall Collisions In Thin Magnetic Nanowires, Andrew Kunz Jan 2009

Field Induced Domain Wall Collisions In Thin Magnetic Nanowires, Andrew Kunz

Physics Faculty Research and Publications

In a two-dimensional magnetic nanowire, it is possible to engineer collisions between two domain walls put into motion by an externally applied field. We show that the topological defects that define the domain wall can be controlled to allow for both domain wall annihilation and preservation during the collisions as long as the wire remains thin. The preservation process can be used to release pinned domain walls from notches with small applied fields.


Dependence Of Domain Wall Structure For Low Field Injection Into Magnetic Nanowires, Andrew Kunz, Sarah C. Reiff Jan 2009

Dependence Of Domain Wall Structure For Low Field Injection Into Magnetic Nanowires, Andrew Kunz, Sarah C. Reiff

Physics Faculty Research and Publications

Micromagnetic simulation is used to model the injection of a domain wall into a magnetic nanowire with field strengths less than the so-called Walker field. This ensures fast, reliable motion of the wall. When the wire is located at the edge of a small injecting disk, a bias field used to control the orientation of the domain wall can reduce the pinning potential of the structure. The low field injection is explained by a simple model, which relies on the topological nature of a domain wall. The technique can quickly inject multiple domain walls with a known magnetic structure.


Antivortex Dynamics In Magnetic Nanostripes, Andrew Kunz, Eric C. Breitbach, Andy J. Smith Jan 2009

Antivortex Dynamics In Magnetic Nanostripes, Andrew Kunz, Eric C. Breitbach, Andy J. Smith

Physics Faculty Research and Publications

In a thin magnetic nanostripe, an antivortex nucleates inside a moving domain wall when driven by an in-plane magnetic field greater than the so-called Walker field. The nucleated antivortex must cross the width of the nanostripe before the domain wall can propagate again, leading to low average domain wall speeds. A large out-of-plane magnetic field, applied perpendicularly to the plane of the nanostripe, inhibits the nucleation of the antivortex leading to fast domain wall speeds for all in-plane driving fields. We present micromagnetic simulation results relating the antivortex dynamics to the strength of the out-of-plane field. An asymmetry in the …


The Temperature Dependence Of Hysteretic Processes In Co Nanowires Arrays, I Astefanoaei, I Dumitru, A Diaconu, L Spinu, A Stancu Jan 2008

The Temperature Dependence Of Hysteretic Processes In Co Nanowires Arrays, I Astefanoaei, I Dumitru, A Diaconu, L Spinu, A Stancu

Physics Faculty Publications

In this paper, the temperature dependence of the hysteretic processes of Co nanowires, squarelly ordered in an array prepared by electrodeposition in nanopores of alumina membranes was analyzed. Both the magnetostatic interactions induced in the nanowires arrays and the thermal stresses (radial, azimuthal and axial stresses), which appear during the cooling of the system (nanowire and alumina template) from room temperature to 3 K was evaluated. The analysis of thermal induced stresses provides useful informations concerning the magnetic anisotropy in the Co nanowires. The temperature dependence of the remanent magnetization and coercitive field as an effect of the induced thermal …


Fast Domain Wall Motion In Nanostripes With Out-Of-Plane Fields, Andrew Kunz, Sarah C. Reiff Jan 2008

Fast Domain Wall Motion In Nanostripes With Out-Of-Plane Fields, Andrew Kunz, Sarah C. Reiff

Physics Faculty Research and Publications

Controlling domain wall motion is important due to the impact on the viability of proposed nanowire devices. One hurdle is slow domain wall speed when driven by fields greater than the Walker field due to nucleation of vortices in the wall. We present simulation results detailing the dynamics of these vortices including the nucleation and subsequent fast ejection of the vortex core leading to fast domain wall speeds. The ejection is due to the reversal of the core moments by an out-of-plane field. The technique can be used to produce domain walls of known orientation, independent of the initial state.


Enhancing Domain Wall Speed In Nanowires With Transverse Magnetic Fields, Andrew Kunz, Sarah C. Reiff Jan 2008

Enhancing Domain Wall Speed In Nanowires With Transverse Magnetic Fields, Andrew Kunz, Sarah C. Reiff

Physics Faculty Research and Publications

Dynamic micromagnetic simulation studies have been completed to observe the motion of a domain wall in a magnetic nanowire in an effort to increase the field-driven domain wall speed. Previous studies have shown that the wire dimensions place a cap on the maximum speed attainable by a domain wall when driven by a magnetic field placed along the direction of the nanowire. Here we present data showing a significant increase in the maximum speed of a domain wall due to the addition of a magnetic field placed perpendicular to the longitudinal driving field. The results are expressed in terms of …


). Size Dependency Of The Elastic Modulus Of Zno Nanowires: Surface Stress Effect, Guofeng Wang, Xiaodong Li Dec 2007

). Size Dependency Of The Elastic Modulus Of Zno Nanowires: Surface Stress Effect, Guofeng Wang, Xiaodong Li

Faculty Publications

Relation between the elastic modulus and the diameter (D) of ZnOnanowires was elucidated using a model with the calculated ZnOsurface stresses as input. We predict for ZnOnanowires due to surface stress effect: (1) when D>20nm, the elastic modulus would be lower than the bulk modulus and decrease with the decreasing diameter, (2) when 20nm>D>2nm, the nanowires with a longer length and a wurtzite crystal structure could be mechanically unstable, and (3) when D<2nm, the elastic modulus would be higher than that of the bulk value and increase with a decrease in nanowire diameter.


Micromagnetics Of The Domain Wall Mobility In Permalloy Nanowires, Andrew Kunz Jun 2007

Micromagnetics Of The Domain Wall Mobility In Permalloy Nanowires, Andrew Kunz

Physics Faculty Research and Publications

The domain wall mobility in long permalloy nanowires with thicknesses of 2-20 nm and widths of 50-200 nm has been simulated. The domain wall is driven into motion by an external magnetic field and the average wall mobility is calculated after the wall has traveled 2.5 mum along the wire. The results were obtained using the three-dimensional dynamic Landau-Lifshitz equation. We find that the domain wall mobility decreases linearly up to the critical field called the Walker field. The decreasing wall mobility is related to the decrease in the dynamic domain wall length as the applied field is increased. The …


Selective Growth Of Single-Crystalline Zno Nanowires On Doped Silicon, Rolf Könenkamp, Robert Campbell Word, M. Dosmailov, J. Meiss, Athavan Nadarajah Jan 2007

Selective Growth Of Single-Crystalline Zno Nanowires On Doped Silicon, Rolf Könenkamp, Robert Campbell Word, M. Dosmailov, J. Meiss, Athavan Nadarajah

Physics Faculty Publications and Presentations

We report the growth of single-crystalline ZnO nanowires on n- and p-type Si wafers by electrodeposition. On strongly doped n-type Si high-quality nanowires can be grown under similar conditions as used for metallic substrates. For low electron concentrations occurring in weakly n-type or in p-type wafers, nanowire growth is inhibited. This difference allows selective growth in strongly n-type areas. The inhibited growth on weakly n-type and p-type wafers can be improved by applying stronger cathodic electrode potentials or by illuminating the growth area. The wires on n-Si show efficient electroluminescence covering the visible and extending into the ultraviolet spectral range.


Micromagnetic Simulations On The Dependence Of Gilbert Damping On Domain Wall Velocities In Magnetic Nanowires, Andrew Kunz, B. Kastor May 2006

Micromagnetic Simulations On The Dependence Of Gilbert Damping On Domain Wall Velocities In Magnetic Nanowires, Andrew Kunz, B. Kastor

Physics Faculty Research and Publications

he dependence of damping on domain wall motion and velocity in Permalloy nanowires is presented. The domain wall motion in isolated two micron long Permalloy nanowires, with a rectangular cross-section 10 nm thick and 100 nm wide, is simulated using the Landau-Lifshitz Gilbert (LLG) simulation.Interpreting LLG dynamics can be difficult due to the dependence of the results on the Gilbert damping parameter alpha. The Walker model also predicts the critical field and domain wall velocity as a function of alpha. For these combined reasons the dependence of the domain wall speeds on the damping parameter is explored.


Simulated Domain Wall Dynamics In Magnetic Nanowires, Andrew Kunz Jan 2006

Simulated Domain Wall Dynamics In Magnetic Nanowires, Andrew Kunz

Physics Faculty Research and Publications

The simulated domain wall dynamics in rectangular 10 nm thick, 2000 nm long Permalloy wires of varying width is presented. In the absence of an applied field the static domain wall length is found to be linearly dependent to the width of the nanowire. As magnetic fields of increasing strength are applied along the wire’s long axis, the domain wall motion changes from a uniform reversal to a steplike reversal. The onset of the stepping motion leads to a decrease in the domain wall speed. By continuing to increase the field it is possible to decrease the time between steps …


Domain-Wall Magnetoresistance Of Co Nanowires, Renat F. Sabirianov, Ashok K. Solanki, J. D. Burton, Sitaram S. Jaswal, Evgeny Y. Tsymbal Aug 2005

Domain-Wall Magnetoresistance Of Co Nanowires, Renat F. Sabirianov, Ashok K. Solanki, J. D. Burton, Sitaram S. Jaswal, Evgeny Y. Tsymbal

Physics Faculty Publications

Using density functional theory implemented within a tight-binding linear muffin-tin orbital method we perform calculations of electronic, magnetic, and transport properties of ferromagnetic free-standing fcc Co wires with diameters up to 1.5 nm. We show that finite-size effects play an important role in these nanowires resulting in oscillatory behavior of electronic charge and the magnetization as a function of the wire thickness, and a nonmonotonic behavior of spin-dependent quantized conductance. We calculate the magnetoresistance (MR) of a domain wall (DW) modeled by a spin-spiral region of finite width sandwiched between two semi-infinite Co wire leads. We find that the DW …


Lattice Thermal Conductance In Nanowires At Low Temperatures: Breakdown And Recovery Of Quantization, Y. Tanaka, F. Yoshida, S. Tamura May 2005

Lattice Thermal Conductance In Nanowires At Low Temperatures: Breakdown And Recovery Of Quantization, Y. Tanaka, F. Yoshida, S. Tamura

Dartmouth Scholarship

The quantization of lattice thermal conductance g normalized by g0=π2k2BT/3h (the universal quantum of thermal conductance) was recently predicted theoretically to take an integer value over a finite range of temperature and then observed experimentally in nanowires with catenoidal contacts. The prediction of this quantization by Rego and Kirczenow [Phys. Rev. Lett. 81, 232 (1998)] relies on a study of only dilatational (longitudinal) vibrational mode in the wires. We study the thermal conductance in catenoidal wires by explicitly calculating the transmission rates of the six distinct vibrational modes (four acoustic and two low-lying optical modes) and applying the Landauer …


Vertical Nanowire Light-Emitting Diode, Rolf Könenkamp, Robert Campbell Word, C. Schlegel Dec 2004

Vertical Nanowire Light-Emitting Diode, Rolf Könenkamp, Robert Campbell Word, C. Schlegel

Physics Faculty Publications and Presentations

We report room-temperature, white-color electroluminescence in vertically oriented ZnO nanowires. Excitonic luminescence around 380 nm is observed as a shoulder on a broader defect-related band covering all of the visible range and centered at 620 nm. The ZnO nanowires are grown in a low-temperature process on SnO2-coated glass substrates, employing a technique that is suitable for large-area applications. The nanowires are robustly encapsulated in a thin polystyrene film deposited from high-molecular-weight solutions. Electron injection occurs through the transparent SnO2 layer, while hole injection is mediated by a p-doped polymer and an evaporated Au contact. Stable device operation …


Vertical Nanowire Transistors With Low Leakage Current, Jie Chen, M. C. Lux-Steiner, Rolf Kӧnenkamp, S. Klaumünzer Aug 2004

Vertical Nanowire Transistors With Low Leakage Current, Jie Chen, M. C. Lux-Steiner, Rolf Kӧnenkamp, S. Klaumünzer

Physics Faculty Publications and Presentations

A vertical field-effect transistor based on semiconductor nanowires is reported. The fabrication of the device uses a self-supporting flexible nanostructured polymer foil as a template and an electrochemical growth technique for the preparation of the semiconductor. The fabrication process is substantially simpler, and the mechanical robustness is strongly increased as compared to the original device. The channel region of the transistor has a diameter of ∼100 nm and a length of ∼50 nm. Operation in the hole depletion mode allows a change of the transfer conductance by ∼50% when the gate voltages is changed in the range ∓1 V. The …


Growth And Transport Properties Of Complementary Germanium Nanowire Field Effect Transistors, Andrew B. Greytak, Lincoln J. Lauhon, Mark S. Gudiksen, Charles M. Lieber May 2004

Growth And Transport Properties Of Complementary Germanium Nanowire Field Effect Transistors, Andrew B. Greytak, Lincoln J. Lauhon, Mark S. Gudiksen, Charles M. Lieber

Faculty Publications

n- and p-type Ge nanowires were synthesized by a multistep process in which axial elongation, via vapor–liquid–solid (VLS) growth, and doping were accomplished in separate chemical vapor deposition steps. Intrinsic, single-crystal, Ge nanowires prepared by Au nanocluster-mediated VLS growth were surface-doped in situ using diborane or phosphine, and then radial growth of an epitaxial Ge shell was used to cap the dopant layer. Field-effect transistors prepared from these Ge nanowires exhibited on currents and transconductances up to 850 µA/µm and 4.9 µA/V, respectively, with device yields of >85%.


Vertical Nanowire Transistor In Flexible Polymer Foil, Jie Chen, Rolf Könenkamp Jun 2003

Vertical Nanowire Transistor In Flexible Polymer Foil, Jie Chen, Rolf Könenkamp

Physics Faculty Publications and Presentations

Fabrication and operation of a vertical nanowire field-effect transistor is reported. The device is prepared by growing vertical wires in the cylindrical pores of a polymer foil stack. The nanowirediameter is approximately 100 nm, the packing density up to 10⁸ cm⁻². The polymer foil stack consists of two polymer layers and an intermediate metal layer. Cylindrical holes are prepared in this stack by using fast ion irradiation and subsequent etching. Well-defined cylindrical openings with diameters between 50 and 150 nm are obtained. The semiconductor growth involves electrodeposition of the p-type quaternary compound CuSCN. Electrical measurements on first devices show transistor …


Modeling Of Hysteresis And Magnetization Curves For Hexagonally Ordered Electrodeposited Nanowires, Petru S. Fodor, Georgy M. Tsoi, Lowell E. Wenger Jan 2003

Modeling Of Hysteresis And Magnetization Curves For Hexagonally Ordered Electrodeposited Nanowires, Petru S. Fodor, Georgy M. Tsoi, Lowell E. Wenger

Physics Faculty Publications

A computational model has been developed to investigate how the magnetostatic interactions affect the hysteresis and magnetization curves for hexagonal arrays of magnetic nanowires. The magnetization coupling between nanowires arises from the stray fields produced by the other nanowires composing the array such that the field at each nanowire is the sum of the external field and the interaction field with the other nanowires. Using only two adjustable parameters: the interaction between nearest neighbors and the width of the Gaussian distribution in switching fields centered around the measuredcoercivity, simulations are compared with the experimentally measuredhysteresis and magnetization curves for electrodepositedCo0.45 …


Zero Magnetization States In Electrodeposited Co0.45fe0.55 Nanowire Arrays, Petru S. Fodor, Georgy M. Tsoi, Lowell E. Wenger Jan 2003

Zero Magnetization States In Electrodeposited Co0.45fe0.55 Nanowire Arrays, Petru S. Fodor, Georgy M. Tsoi, Lowell E. Wenger

Physics Faculty Publications

Co0.45Fe0.55 alloy nanowires with 12 to 35 nm diameter and 12 μm length were fabricated by electrodeposition in porous anodic alumina templates. The initial magnetization curves reveal that the zero magnetization state is not unique and is determined by the field history (acdemagnetization process) leading to the zero average moment state. For acdemagnetization processes with the field applied parallel to the nanowire axis, the subsequent magnetization curves suggest that an individual nanowire behaves as a single domain with neighboring nanowires being antiparallel to each other in the zero magnetization state. However, for a demagnetization process with the field applied perpendicular …