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Articles 181 - 210 of 479
Full-Text Articles in Condensed Matter Physics
Hartmann Characterization Of The Peem-3 Aberration-Corrected X-Ray Photoemission Electron Microscope, A. Scholl, M. A. Marcus, A. Doran, J. R. Nasiatka, A. T. Young, A. A. Macdowell, R. Streubel, N. Kent, J. Feng, W. Wan, H. A. Padmore
Hartmann Characterization Of The Peem-3 Aberration-Corrected X-Ray Photoemission Electron Microscope, A. Scholl, M. A. Marcus, A. Doran, J. R. Nasiatka, A. T. Young, A. A. Macdowell, R. Streubel, N. Kent, J. Feng, W. Wan, H. A. Padmore
Robert Streubel Papers
Aberration correction by an electron mirror dramatically improves the spatial resolution and transmission of photoemission electron microscopes. We will review the performance of the recently installed aberration corrector of the X-ray Photoemission Electron Microscope PEEM-3 and show a large improvement in the efficiency of the electron optics. Hartmann testing is introduced as a quantitative method to measure the geometrical aberrations of a cathode lens electron microscope. We find that aberration correction leads to an order of magnitude reduction of the spherical aberrations, suggesting that a spatial resolution of below 100 nm is possible at 100% transmission of the optics when …
Resonant Tunneling Across A Ferroelectric Domain Wall, M. Li, L. L. Tao, J. P. Velev, Evgeny Y. Tsymbal
Resonant Tunneling Across A Ferroelectric Domain Wall, M. Li, L. L. Tao, J. P. Velev, Evgeny Y. Tsymbal
Evgeny Tsymbal Publications
Motivated by recent experimental observations, we explore electron transport properties of a ferroelectric tunnel junction (FTJ) with an embedded head-to-head ferroelectric domain wall, using first-principles density-functional theory calculations. We consider a FTJ with La0.5Sr0.5MnO3 electrodes separated by a BaTiO3 barrier layer and show that an in-plane charged domain wall in the ferroelectric BaTiO3 can be induced by polar interfaces. The resulting V-shaped electrostatic potential profile across the BaTiO3 layer creates a quantum well and leads to the formation of a two-dimensional electron gas, which stabilizes the domain wall. The confined electronic states …
Dielectric Properties Of Thin Cr2o3 Films Grown On Elemental And Oxide Metallic Substrates, Ather Mahmood, Mike Street, Will Echtenkamp, Chun Pui Kwan, Jonathan P. Bird, Christian Binek
Dielectric Properties Of Thin Cr2o3 Films Grown On Elemental And Oxide Metallic Substrates, Ather Mahmood, Mike Street, Will Echtenkamp, Chun Pui Kwan, Jonathan P. Bird, Christian Binek
Christian Binek Publications
In an attempt to optimize leakage characteristics of α-Cr2O3 thin films, its dielectric properties were investigated at local and macroscopic scale. The films were grown on Pd(111), Pt(111), and V2O3 (0001), supported on Al2O3 substrate. The local conductivity was measured by conductive atomic force microscopy mapping of Cr2O3 surfaces, which revealed the nature of defects that formed conducting paths with the bottom Pd or Pt layer. A strong correlation was found between these electrical defects and the grain boundaries revealed in the corresponding topographic scans. In comparison, …
Polarization-Controlled Modulation Doping Of A Ferroelectric From First Principles, Xiaohui Liu, Evgeny Y. Tsymbal, Karin M. Rabe
Polarization-Controlled Modulation Doping Of A Ferroelectric From First Principles, Xiaohui Liu, Evgeny Y. Tsymbal, Karin M. Rabe
Evgeny Tsymbal Publications
In a ferroelectric field effect transistor (FeFET), it is generally assumed that the ferroelectric gate plays a purely electrostatic role. Recently it has been shown that in some cases, which could be called “active FeFETs,” electronic states in the ferroelectric contribute to the device conductance as the result of a modulation doping effect in which carriers are transferred from the channel into the ferroelectric layers near the interface. Here we report first-principles calculations and model analysis to elucidate the various aspects of this mechanism and to provide guidance in materials choices and interface termination for optimizing the on-off ratio, using …
Nanostructural Origin Of Semiconductivity And Large Magnetoresistance In Epitaxial Nico2O4/Al2O3 Thin Films, Congmian Zhen, Xiaozhe Zhang, Wengang Wei, Wenzhe Guo, Ankit Pant, Xiaoshan Xu, Jian Shen, Li Ma, Denglu Hou
Nanostructural Origin Of Semiconductivity And Large Magnetoresistance In Epitaxial Nico2O4/Al2O3 Thin Films, Congmian Zhen, Xiaozhe Zhang, Wengang Wei, Wenzhe Guo, Ankit Pant, Xiaoshan Xu, Jian Shen, Li Ma, Denglu Hou
Xiaoshan Xu Papers
Despite low resistivity (~1 mΩ cm), metallic electrical transport has not been commonly observed in inverse spinel NiCo2O4, except in certain epitaxial thin films. Previous studies have stressed the effect of valence mixing and the degree of spinel inversion on the electrical conduction of NiCo2O4 films. In this work, we studied the effect of nanostructural disorder by comparing the NiCo2O4 epitaxial films grown on MgAl2O4 (1 1 1) and on Al2O3 (0 0 1) substrates. Although the optimal growth conditions are similar for the …
Structure And Magnetism Of Mn5ge3 Nanoparticles, Onur Tosun, Mohammed Salehi-Fashami, Balamurugan Balasubramanian, Ralph Skomski, David J. Sellmyer, George C. Hadjipanayis
Structure And Magnetism Of Mn5ge3 Nanoparticles, Onur Tosun, Mohammed Salehi-Fashami, Balamurugan Balasubramanian, Ralph Skomski, David J. Sellmyer, George C. Hadjipanayis
Nebraska Center for Materials and Nanoscience: Faculty Publications
In this work, we investigated the magnetic and structural properties of isolated Mn5Ge3 nanoparticles prepared by the cluster-beam deposition technique. Particles with sizes between 7.2 and 12.6 nm were produced by varying the argon pressure and power in the cluster gun. X-ray diffraction (XRD)and selected area diffraction (SAD) measurements show that the nanoparticles crystallize in the hexagonal Mn5Si3-type crystal structure, which is also the structure of bulk Mn5Ge3. The temperature dependence of the magnetization shows that the as-made particles are ferromagnetic at room temperature and have slightly different Curie …
Structural, Magnetic, And Electron-Transport Properties Of Epitaxial Mn2Ptsn Films, Y. Jin, Shah R. Valloppilly, Parashu Kharel, Jace Waybright, Pavel V. Lukashev, Xingzhong Li, David J. Sellmyer
Structural, Magnetic, And Electron-Transport Properties Of Epitaxial Mn2Ptsn Films, Y. Jin, Shah R. Valloppilly, Parashu Kharel, Jace Waybright, Pavel V. Lukashev, Xingzhong Li, David J. Sellmyer
Nebraska Center for Materials and Nanoscience: Faculty Publications
The growth of new magnetic materials on suitable insulating substrates is an important part of the development of spin-electronics devices for memory or information processing. Epitaxial thin films of Mn2PtSn were grown on a MgO [001] substrate by magnetron co-sputtering of the constituents. Structural, magnetic, and electron-transport properties were investigated. The epitaxial Mn2PtSn film has an inverse tetragonal structure with the c-axis aligned in the plane of the MgO substrate. The lattice constants determined using XRD and TEM analysis are c=6.124Å and a=b=4.505Å. The orientation of Mn2PtSn c-axis which …
Multi-Walled Carbon Nanotube-Coated Spiral Coils For Loss Reduction In Wireless Power Transfer Systems, Kamran Keramatnejad, Dawei Li, Hossein Rabiee Golgir, Loic Constantin, Xi Huang, Qiming Zou, Jean-Francois Silvain, Stephen Ducharme, Yongfeng Lu
Multi-Walled Carbon Nanotube-Coated Spiral Coils For Loss Reduction In Wireless Power Transfer Systems, Kamran Keramatnejad, Dawei Li, Hossein Rabiee Golgir, Loic Constantin, Xi Huang, Qiming Zou, Jean-Francois Silvain, Stephen Ducharme, Yongfeng Lu
Stephen Ducharme Publications
Realization of high efficiency and long transmission range in high-frequency wireless power transfer (WPT) systems has always been hindered by the increased resistance due to the eddy current loss occurring in the inductive coils. In this study, multi-walled carbon nanotube-coated copper (MWCNT-Cu) coils are successfully introduced to address this limitation by implementing the frequency-inert MWCNT channels along with using their high-surface areas to realize the electromagnetic shielding of the Cu substrate through multiple reflection mechanisms. At a frequency of 15 MHz, the resistance of the individual MWCNT-Cu coil was reduced to less than 40% of its original value for primitive …
A Brief Review Of Ferroelectric Control Of Magnetoresistance In Organic Spin Valves, Xiaoshan Xu
A Brief Review Of Ferroelectric Control Of Magnetoresistance In Organic Spin Valves, Xiaoshan Xu
Xiaoshan Xu Papers
Magnetoelectric coupling has been a trending research topic in both organic and inorganic materials and hybrids. The concept of controlling magnetism using an electric field is particularly appealing in energy efficient applications. In this spirit, ferroelectricity has been introduced to organic spin valves to manipulate the magneto transport, where the spin transport through the ferromagnet/organic spacer interfaces (spinterface) are under intensive study. The ferroelectric materials in the organic spin valves provide a knob to vary the interfacial energy alignment and the interfacial crystal structures, both are critical for the spin transport. In this review, we introduce the recent efforts of …
The Promise Of Piezoelectric Polymers, Timothy D. Usher, Kimberley R. Cousins, Renwu Zhang, Stephen Ducharme
The Promise Of Piezoelectric Polymers, Timothy D. Usher, Kimberley R. Cousins, Renwu Zhang, Stephen Ducharme
Stephen Ducharme Publications
Recent advances provide new opportunities in the field of polymer piezoelectric materials. Piezoelectric materials provide unique insights to the fundamental understanding of the solid state. In addition, piezoelectric materials have a wide range of applications, representing billions of dollars of commercial applications. However, inorganic piezoelectric materials have limitations that polymer ferroelectric materials can overcome, if certain challenges can be addressed. This mini-review is a practical summary of the current research and future directions in the investigation and application of piezoelectric materials with an emphasis on polymeric piezoelectric materials. We will assume that the reader is well versed in the subject …
Spin Hall And Nernst Effects Of Weyl Magnons, Vladimir Zyuzin, Alexey Kovalev
Spin Hall And Nernst Effects Of Weyl Magnons, Vladimir Zyuzin, Alexey Kovalev
Department of Physics and Astronomy: Faculty Publications
In this paper, we present a simple model of a three-dimensional insulating magnetic structure which represents a magnonic analog of the layered electronic system described by A. A. Burkov and L. Balents [Phys. Rev. Lett. 107, 127205 (2011)]. In particular, our model realizes Weyl magnons as well as surface states with a Dirac spectrum. In this model, the Dzyaloshinskii-Moriya interaction is responsible for the separation of opposite Weyl points in momentum space. We calculate the intrinsic (due to the Berry curvature) transport properties of Weyl and so-called anomalous Hall effect magnons. The results are compared with fermionic …
Isostructural Metal-Insulator Transition In Vo2, D. Lee, B. Chung, Y. Shi, G.-Y. Kim, Neil Campbell, F. Xue, K. Song, S.-Y. Choi, J. P. Podkaminer, T. H. Kim, P. J. Ryan, J.-W. Kim, Tula R. Paudel, J.-H. Kang, J. W. Spinuzzi, D. A. Tenne, Evgeny Y. Tsymbal, M. S. Rzchowski, L. Q. Chen, J. Lee, Chang-Beom Eom
Isostructural Metal-Insulator Transition In Vo2, D. Lee, B. Chung, Y. Shi, G.-Y. Kim, Neil Campbell, F. Xue, K. Song, S.-Y. Choi, J. P. Podkaminer, T. H. Kim, P. J. Ryan, J.-W. Kim, Tula R. Paudel, J.-H. Kang, J. W. Spinuzzi, D. A. Tenne, Evgeny Y. Tsymbal, M. S. Rzchowski, L. Q. Chen, J. Lee, Chang-Beom Eom
Evgeny Tsymbal Publications
No abstract provided.
Towards A Strong Spin–Orbit Coupling Magnetoelectric Transistor, Peter Dowben, Christian Binek, Kai Zhang, Lu Wang, Wai-Ning Mei, Jonathan P. Bird, Uttam Singisetti, Xia Hong, Kang L. Wang, Dmitri Nikonov
Towards A Strong Spin–Orbit Coupling Magnetoelectric Transistor, Peter Dowben, Christian Binek, Kai Zhang, Lu Wang, Wai-Ning Mei, Jonathan P. Bird, Uttam Singisetti, Xia Hong, Kang L. Wang, Dmitri Nikonov
Peter Dowben Publications
Here, we outline magnetoelectric (ME) device concepts based on the voltage control of the interface magnetism of an ME antiferromagnet gate dielectric formed on a very thin semiconductor channel with large spin–orbit coupling (SOC). The emphasis of the ME spin field-effect transistors (ME spin FET) is on an antiferromagnet spin–orbit read logic device and a ME spin-FET multiplexer. Both spin-FET schemes exploit the strong SOC in the semiconducting channel materials but remain dependent on the voltage-induced switching of an ME, so that the switching time is limited only by the switching dynamics of the ME. The induced exchange field spin …
Anisotropy And Phonon Modes From Analysis Of The Dielectric Function Tensor And The Inverse Dielectric Function Tensor Of Monoclinic Yttrium Orthosilicate, Alyssa Mock, Rafal Korlacki, Sean Knight, Mathias Schubert
Anisotropy And Phonon Modes From Analysis Of The Dielectric Function Tensor And The Inverse Dielectric Function Tensor Of Monoclinic Yttrium Orthosilicate, Alyssa Mock, Rafal Korlacki, Sean Knight, Mathias Schubert
Department of Electrical and Computer Engineering: Faculty Publications
We determine the frequency dependence of the four independent Cartesian tensor elements of the dielectric function for monoclinic symmetry Y2SiO5 using generalized spectroscopic ellipsometry from 40–1200 cm−1. Three different crystal cuts, each perpendicular to a principle axis, are investigated. We apply our recently described augmentation of lattice anharmonicity onto the eigendielectric displacement vector summation approach [A.Mock et al., Phys. Rev. B 95, 165202 (2017)], and we present and demonstrate the application of an eigendielectric displacement loss vector summation approach with anharmonic broadening. We obtain an excellent match between all measured and model-calculated dielectric …
Magnetic Skyrmion Bubble Motion Driven By Surface Acoustic Waves, Rabindra Nepal, Utkan Güngördü, Alexey Kovalev
Magnetic Skyrmion Bubble Motion Driven By Surface Acoustic Waves, Rabindra Nepal, Utkan Güngördü, Alexey Kovalev
Department of Physics and Astronomy: Faculty Publications
We study the dynamical control of a magnetic skyrmion bubble by using counter-propagating surface acoustic waves (SAWs) in a ferromagnet. First, we determine the bubble mass and derive the force due to SAWs acting on a magnetic bubble using Thiele's method. The force that pushes the bubble is proportional to the strain gradient for the major strain component. We then study the dynamical pinning and motion of magnetic bubbles by SAWs in a nanowire. In a disk geometry, we propose a SAWs-driven skyrmion bubble oscillator with two resonant frequencies.
Elevated Temperature Dependence Of The Anisotropic Visible-To-Ultraviolet Dielectric Function Of Monoclinic Β-Ga2o3, Alyssa Mock, Jeremy Vanderslice, Rafal Korlacki, John A. Woollam, Mathias Schubert
Elevated Temperature Dependence Of The Anisotropic Visible-To-Ultraviolet Dielectric Function Of Monoclinic Β-Ga2o3, Alyssa Mock, Jeremy Vanderslice, Rafal Korlacki, John A. Woollam, Mathias Schubert
Department of Electrical and Computer Engineering: Faculty Publications
We report on the temperature dependence of the dielectric tensor elements of n-type conductive β-Ga2O3 from 22 °C to 550 °C in the spectral range of 1.5 eV–6.4 eV. We present the temperature dependence of the excitonic and band-to-band transition energy parameters using a previously described eigendielectric summation approach [A. Mock et al., Phys. Rev. B 96, 245205 (2017)]. We utilize a Bose-Einstein analysis of the temperature dependence of the observed transition energies and reveal electron coupling with average phonon temperature in excellent agreement with the average over all longitudinal phonon plasmon coupled modes reported previously [M. …
Magnetism Of New Metastable Cobalt-Nitride Compounds, Balamuruga Balamurugan, Xin Zhao, Shah R. Valloppilly, Sumit Beniwal, Ralph Skomski, Anandakumar Sarella, Yunlong Jin, Xingzhong Li, Xiaoshan Xu, Huibo Cao, Haohan Wang, Axel Enders, Cai-Zhuang Wang, Kai-Ming Ho, David J. Sellmyer
Magnetism Of New Metastable Cobalt-Nitride Compounds, Balamuruga Balamurugan, Xin Zhao, Shah R. Valloppilly, Sumit Beniwal, Ralph Skomski, Anandakumar Sarella, Yunlong Jin, Xingzhong Li, Xiaoshan Xu, Huibo Cao, Haohan Wang, Axel Enders, Cai-Zhuang Wang, Kai-Ming Ho, David J. Sellmyer
Nebraska Center for Materials and Nanoscience: Faculty Publications
The search for new magnetic materials with high magnetization and magnetocrystalline anisotropy is important for a wide range of applications including information and energy processing. There is only a limited number of naturally occurring magnetic compounds that are suitable. This situation stimulates an exploration of new phases that occur far from thermal-equilibrium conditions, but their stabilization is generally inhibited due to high positive formation energies. Here a nanocluster-deposition method has enabled the discovery of a set of new non-equilibrium Co-N intermetallic compounds. The experimental search was assisted by computational methods including adaptive-genetic-algorithm and electronic- structure calculations. Conventional wisdom is that …
Honeycomb Lattice Na2iro3 At High Pressures: A Robust Spin-Orbit Mott Insulator, Xiaoxiang Xi, Xiangyan Bo, X. S. Xu, P. P. Kong, Z. Liu, X. G. Hong, C. Q. Jin, G. Cao, Xiangang Wan, G. L. Carr
Honeycomb Lattice Na2iro3 At High Pressures: A Robust Spin-Orbit Mott Insulator, Xiaoxiang Xi, Xiangyan Bo, X. S. Xu, P. P. Kong, Z. Liu, X. G. Hong, C. Q. Jin, G. Cao, Xiangang Wan, G. L. Carr
Xiaoshan Xu Papers
The honeycomb iridate Na2IrO3 has received much attention as a candidate to realize a quantum spin liquid state, but the nature of its insulating state remains controversial. We found that the material exhibits structural transitions at 3 and 10 GPa. The former is accompanied by 166-meV suppression of the activation gap, but the energies for the low-lying interband transitions change by less than 10 meV. This can be reconciled in a picture in which the application of high pressure barely shifts the electronic bands, but rather merely broadens them. First-principles calculations uncover a strong correlation between the …
Tuning The Neel Temperature Of Hexagonal Ferrites By Structural Distortion, Kishan Sinha, Haohan Wang, Xiao Wang, Liying Zhou, Yuewei Yin, Wenbin Wang, Xuemei Cheng, David J. Keavney, Huibo Cao, Yaohua Liu, Xifan Wu, Xiaoshan Xu
Tuning The Neel Temperature Of Hexagonal Ferrites By Structural Distortion, Kishan Sinha, Haohan Wang, Xiao Wang, Liying Zhou, Yuewei Yin, Wenbin Wang, Xuemei Cheng, David J. Keavney, Huibo Cao, Yaohua Liu, Xifan Wu, Xiaoshan Xu
Xiaoshan Xu Papers
To tune the magnetic properties of hexagonal ferrites, a family of magnetoelectric multiferroic materials, by atomic-scale structural engineering, we studied the effect of structural distortion on the magnetic ordering temperature (TN) in these materials. Using the symmetry analysis, we show that unlike most antiferromagnetic rare-earth transition-metal perovskites, a larger structural distortion leads to a higher TN in hexagonal ferrites and manganites, because the K3 structural distortion induces the three-dimensional magnetic ordering, which is forbidden in the undistorted structure by symmetry. We also revealed a nearlinear relation between TN and the tolerance factor and a …
Stabilization And Control Of Majorana Bound States With Elongated Skyrmions, Utkan Güngördü, Shane Sandhoefner, Alexey Kovalev
Stabilization And Control Of Majorana Bound States With Elongated Skyrmions, Utkan Güngördü, Shane Sandhoefner, Alexey Kovalev
Department of Physics and Astronomy: Faculty Publications
We show that elongated magnetic skyrmions can host Majorana bound states in a proximity-coupled two-dimensional electron gas sandwiched between a chiral magnet and an s-wave superconductor. Our proposal requires stable skyrmions with unit topological charge, which can be realized in a wide range of multilayer magnets, and it allows quantum information transfer by using standard methods in spintronics via skyrmion motion. We also show how braiding operations can be realized in our proposal.
Focused Electron-Beam-Induced Deposition For Fabrication Of Highly Durable And Sensitive Metallic Afm-Ir Probes, Wen Qian, Shuo Sun, Jingfeng Song, Charles Nguyen, Stephen Ducharme, Joesph A. Turner
Focused Electron-Beam-Induced Deposition For Fabrication Of Highly Durable And Sensitive Metallic Afm-Ir Probes, Wen Qian, Shuo Sun, Jingfeng Song, Charles Nguyen, Stephen Ducharme, Joesph A. Turner
Stephen Ducharme Publications
We report on the fabrication of metallic, ultra-sharp atomic force microscope tips for localized nanoscale infrared (IR) spectrum measurements by using focused electron-beam-induced deposition of platinum or tungsten. The tip length can be controlled by changing the duration time of the electron beam. Probes of 12.0 ± 5.0 nm radius-of-curvature can be routinely produced with high repeatability and near-100% yield. The near-field-enhancement appears stronger at the extremity of the metallic tip, compared with commercial pristine silicon-nitride probe tip. Finally, the performance of the modified metallic tips is demonstrated by imaging PVDF and PMMA thin films, which shows that spatial resolution …
Saw Assisted Domain Wall Motion In Co/Pt Multilayers, Westin Edrington, Uday Singh, Maya Abo Dominguez, James Rehwaldt Alexander, Rabindra Nepal, Shireen Adenwalla
Saw Assisted Domain Wall Motion In Co/Pt Multilayers, Westin Edrington, Uday Singh, Maya Abo Dominguez, James Rehwaldt Alexander, Rabindra Nepal, Shireen Adenwalla
Shireen Adenwalla Papers
The motion of domain walls in thin ferromagnetic films is of both fundamental and technological interest. In particular, the ability to use drivers other than magnetic fields to control the positions of domain walls could be exciting for memory applications. Here, we show that high frequency dynamic strain produced by surface acoustic waves is an efficient driver of magnetic domain walls in ferromagnetic films with perpendicular anisotropy. A standing surface acoustic wave of resonant frequency 96.6MHz increases the domain wall velocities in thin films of [Co/Pt]n by an order of magnitude compared to magnetic fields alone. This effect is highly …
Magnetocrystalline Anisotropy Of "-Fe2o3, Imran Ahamed, Rohilt Pathak, Arti Kashyap
Magnetocrystalline Anisotropy Of "-Fe2o3, Imran Ahamed, Rohilt Pathak, Arti Kashyap
Nebraska Center for Materials and Nanoscience: Faculty Publications
The epsilon Fe2O3 phase of iron oxide has been studied to understand the spin structure and the magnetocrystalline anisotropy in the bulk and in thin films of "-Fe2O3 and Co-doped "-Fe2O3. The preferential magnetization direction in the nanoparticles of "-Fe2O3 is along the a-axis [M. Gich et al., Chem. Mater. 18, 3889 (2006)]. Compared to the bulk band gap of 1.9 eV, the thin-film band gap is reduced to 1.3 eV in the Co-free films and to 0.7 eV in the film with partial …
Texture Development And Coercivity Enhancement In Cast Alnico 9 Magnets, Wenyong Zhang, Shah Valloppilly, Xingzhong Li, Lanping Yue, Ralph Skomski, Iver Anderson, Matthew Kramer, Wei Tang, Jeff Shield, David J. Sellmyer
Texture Development And Coercivity Enhancement In Cast Alnico 9 Magnets, Wenyong Zhang, Shah Valloppilly, Xingzhong Li, Lanping Yue, Ralph Skomski, Iver Anderson, Matthew Kramer, Wei Tang, Jeff Shield, David J. Sellmyer
Nebraska Center for Materials and Nanoscience: Faculty Publications
The effect of Y addition and magnetic field on texture and magnetic properties of arc-melted alnico 9 magnets has been investigated. Small additions of Y (1.5 wt.%) develop a (200) texture for the arc-melted alnico 9 magnet. Such a texture is hard to form in cast samples. To achieve this goal, we set up a high-field annealing system with a maximum operation temperature of 12500 C. This system enabled annealing in a field of 45 kOe with subsequent draw annealing for the solutionized buttons; we have been able to substantially increase remanence ratio and coercivity, from 0.70 and 1200 …
Prediction Of A Mobile Two-Dimensional Electron Gas At The Lasco3/Basno3(001) Interface, Tula R. Paudel, Evgeny Y. Tsymbal
Prediction Of A Mobile Two-Dimensional Electron Gas At The Lasco3/Basno3(001) Interface, Tula R. Paudel, Evgeny Y. Tsymbal
Evgeny Tsymbal Publications
Two-dimensional electron gases (2DEG) at oxide interfaces, such as LaAlO3/SrTiO3 (001), have aroused significant interest due to their high carrier density (∼1014 cm−2) and strong lateral confinement (∼1 nm). However, these 2DEGs are normally hosted by the weakly dispersive and degenerate d bands (e.g., Ti-3d bands), which are strongly coupled to the lattice, causing mobility of such 2DEGs to be relatively low at room temperature (∼1 cm2/Vs). Here, we propose using oxide host materials with the conduction bands formed from s electrons to increase carrier mobility and soften its temperature dependence. Using …
Generalized Ellipsometry On Complex Nanostructures And Low-Symmetry Materials, Alyssa Mock
Generalized Ellipsometry On Complex Nanostructures And Low-Symmetry Materials, Alyssa Mock
Department of Electrical and Computer Engineering: Dissertations, Theses, and Student Research
In this thesis, complex anisotropic materials are investigated and characterized by generalized ellipsometry. In recent years, anisotropic materials have gained considerable interest for novel applications in electronic and optoelectronic devices, mostly due to unique properties that originate from reduced crystal symmetry. Examples include white solid-state lighting devices which have become ubiquitous just recently, and the emergence of high-power, high-voltage electronic transistors and switches in all-electric vehicles. The incorporation of single crystalline material with low crystal symmetry into novel device structures requires reconsideration of existing optical characterization approaches. Here, the generalized ellipsometry concept is extended to include applications for materials with …
Epitaxial Thin Films Of Dirac Semimetal Antiperovskite Cu3Pdn, C. X. Quintela, N. Campbell, D. F. Shao, J. Irwin, D. T. Harris, L. Lie, T. J. Anderson, N. Reiser, X. Q. Pan, Evgeny Y. Tsymbal, M. S. Rzchowski, Chang-Beom Eom
Epitaxial Thin Films Of Dirac Semimetal Antiperovskite Cu3Pdn, C. X. Quintela, N. Campbell, D. F. Shao, J. Irwin, D. T. Harris, L. Lie, T. J. Anderson, N. Reiser, X. Q. Pan, Evgeny Y. Tsymbal, M. S. Rzchowski, Chang-Beom Eom
Evgeny Tsymbal Publications
The growth and study of materials showing novel topological states of matter is one of the frontiers in condensed matter physics. Among this class of materials, the nitride antiperovskite Cu3PdN has been proposed as a new three-dimensional Dirac semimetal. However, the experimental realization of Cu3PdN and the consequent study of its electronic properties have been hindered due to the difficulty of synthesizing this material. In this study, we report fabrication and both structural and transport characterization of epitaxial Cu3PdN thin films grown on (001)-oriented SrTiO3 substrates by reactive magnetron sputtering and post-annealed in …
Surfaces And Interfaces Of Magnetoelectric Oxide Systems, Shi Cao
Surfaces And Interfaces Of Magnetoelectric Oxide Systems, Shi Cao
Department of Physics and Astronomy: Dissertations, Theses, and Student Research
Magnetoelectric materials Cr2O3, hexagonal LuFeO3 and YbFeO3 are studied in this thesis. The surface of chromia (Cr2O3) has a surface electronic structure distinct from the bulk. Our work shows that placing a Cr2O3 single crystal into a single domain state will result in net Cr2O3 spin polarization at the boundary, even in the presence of a gold overlayer. From the Cr 2p3=2 X-ray magnetic circular dichroism signal, there is clear evidence of interface polarization with overlayers of both Pd and Pt on chromia. Cobalt thin films on Cr2O3(0001) show larger magnetic contrast in magnetic force microscopy indicating enhancement of perpendicular …
Three-Dimensional Nanomagnetism, Amalio Fernández-Pacheco, Robert Streubel, Olivier Fruchart, Riccardo Hertel, Peter Fischer, Russell P. Cowburn
Three-Dimensional Nanomagnetism, Amalio Fernández-Pacheco, Robert Streubel, Olivier Fruchart, Riccardo Hertel, Peter Fischer, Russell P. Cowburn
Robert Streubel Papers
Magnetic nanostructures are being developed for use in many aspects of our daily life, spanning areas such as data storage, sensing and biomedicine. Whereas patterned nanomagnets are traditionally two-dimensional planar structures, recent work is expanding nanomagnetism into three dimensions; a move triggered by the advance of unconventional synthesis methods and the discovery of new magnetic effects. In three-dimensional nanomagnets more complex magnetic configurations become possible, many with unprecedented properties. Here we review the creation of these structures and their implications for the emergence of new physics, the development of instrumentation and computational methods, and exploitation in numerous applications.
Nanosecond X-Ray Photon Correlation Spectroscopy On Magnetic Skyrmions, M. H. Seaberg, B. Holladay, J. C.T. Lee, M. Sikorski, A. H. Reid, S. A. Montoya, G. L. Dakovski, J. D. Koralek, G. Coslovich, S. Moeller, W. F. Schlotter, R. Streubel, S. D. Kevan, P. Fischer, E. E. Fullerton, J. L. Turner, F. J. Decker, S. K. Sinha, S. Roy, J. J. Turner
Nanosecond X-Ray Photon Correlation Spectroscopy On Magnetic Skyrmions, M. H. Seaberg, B. Holladay, J. C.T. Lee, M. Sikorski, A. H. Reid, S. A. Montoya, G. L. Dakovski, J. D. Koralek, G. Coslovich, S. Moeller, W. F. Schlotter, R. Streubel, S. D. Kevan, P. Fischer, E. E. Fullerton, J. L. Turner, F. J. Decker, S. K. Sinha, S. Roy, J. J. Turner
Robert Streubel Papers
We report an x-ray photon correlation spectroscopy method that exploits the recent development of the two-pulse mode at the Linac Coherent Light Source. By using coherent resonant x-ray magnetic scattering, we studied spontaneous fluctuations on nanosecond time scales in thin films of multilayered Fe/Gd that exhibit ordered stripe and Skyrmion lattice phases. The correlation time of the fluctuations was found to differ between the Skyrmion phase and near the stripe-Skyrmion boundary. This technique will enable a significant new area of research on the study of equilibrium fluctuations in condensed matter.