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Full-Text Articles in Physics

Voltage Controlled Néel Vector Rotation In Zero Magnetic Field, Ather Mahmood, Will Echtenkamp, Mike Street, Jun Lei Wang, Shi Cao, Takashi Komesu, Peter Dowben, Pratyush Buragohain, Haidong Lu, Alexei Gruverman, Arun Parthasarathy, Shaloo Rakheja, Christian Binek Dec 2021

Voltage Controlled Néel Vector Rotation In Zero Magnetic Field, Ather Mahmood, Will Echtenkamp, Mike Street, Jun Lei Wang, Shi Cao, Takashi Komesu, Peter Dowben, Pratyush Buragohain, Haidong Lu, Alexei Gruverman, Arun Parthasarathy, Shaloo Rakheja, Christian Binek

Peter Dowben Publications

Multi-functional thin films of boron (B) doped Cr2O3 exhibit voltage-controlled and nonvolatile Néel vector reorientation in the absence of an applied magnetic field, H. Toggling of antiferromagnetic states is demonstrated in prototype device structures at CMOS compatible temperatures between 300 and 400 K. The boundary magnetization associated with the Néel vector orientation serves as state variable which is read via magnetoresistive detection in a Pt Hall bar adjacent to the B:Cr2O3 film. Switching of the Hall voltage between zero and non-zero values implies Néel vector rotation by 90 degrees. Combined magnetometry, spin resolved inverse …


Quantum State Tomography Of Molecules By Ultrafast Diffraction, Ming Zhang, Shuqiao Zhang, Yanwei Xiong, Hankai Zhang, Anatoly A. Ischenko, Oriol Vendrell, Xiaolong Dong, Xiangxu Mu, Martin Centurion, Haitan Xu, R. J.Dwayne Miller, Zheng Li Dec 2021

Quantum State Tomography Of Molecules By Ultrafast Diffraction, Ming Zhang, Shuqiao Zhang, Yanwei Xiong, Hankai Zhang, Anatoly A. Ischenko, Oriol Vendrell, Xiaolong Dong, Xiangxu Mu, Martin Centurion, Haitan Xu, R. J.Dwayne Miller, Zheng Li

Martin Centurion Publications

Ultrafast electron diffraction and time-resolved serial crystallography are the basis of the ongoing revolution in capturing at the atomic level of detail the structural dynamics of molecules. However, most experiments capture only the probability density of the nuclear wavepackets to determine the time-dependent molecular structures, while the full quantum state has not been accessed. Here, we introduce a framework for the preparation and ultrafast coherent diffraction from rotational wave packets of molecules, and we establish a new variant of quantum state tomography for ultrafast electron diffraction to characterize the molecular quantum states. The ability to reconstruct the density matrix, which …


Ferromagnetic Resonances In Single-Crystal Yttrium Iron Garnet Nanofilms Fabricated By Metal-Organic Decomposition, Szu Fan Wang, Kayetan Chorazewicz, Suvechhya Lamichhane, Ronald A. Parrott, Stefano Cabrini, Peter Fischer, Noah Kent, John H. Turner, Takayuki Ishibashi, Zachary Parker Frohock, Jacob J. Wisser, Peng Li, Ruthi Zielinski, Bryce Herrington, Yuri Suzuki, Mingzhong Wu, Keiko Munechika, Carlos Pina-Hernandez, Robert Streubel, Allen A. Sweet Oct 2021

Ferromagnetic Resonances In Single-Crystal Yttrium Iron Garnet Nanofilms Fabricated By Metal-Organic Decomposition, Szu Fan Wang, Kayetan Chorazewicz, Suvechhya Lamichhane, Ronald A. Parrott, Stefano Cabrini, Peter Fischer, Noah Kent, John H. Turner, Takayuki Ishibashi, Zachary Parker Frohock, Jacob J. Wisser, Peng Li, Ruthi Zielinski, Bryce Herrington, Yuri Suzuki, Mingzhong Wu, Keiko Munechika, Carlos Pina-Hernandez, Robert Streubel, Allen A. Sweet

Robert Streubel Papers

Tunable microwave and millimeter wave oscillators and bandpass filters with ultra-low phase noise play a critical role in electronic devices, including wireless communication, microelectronics, and quantum computing. Magnetic materials, such as yttrium iron garnet (YIG), possess ultra-low phase noise and a ferromagnetic resonance tunable up to tens of gigahertz. Here, we report structural and magnetic properties of single-crystal 60 and 130 nm-thick YIG films prepared by metal-organic decomposition epitaxy. These films, consisting of multiple homoepitaxially grown monolayers, are atomically flat and possess magnetic properties similar to those grown with liquid-phase epitaxy, pulsed laser deposition, and sputtering. Our approach does not …


Conformer-Specific Photochemistry Imaged In Real Space And Time, E. G. Champenois, D. M. Sanchez, J. Yang, J. P. Figueira Nunes, A. Attar, Martin Centurion, R. Forbes, M. Gühr, K. Hegazy, F. Ji, S. K. Saha, Y. Liu, M. F. Lin, D. Luo, B. Moore, X. Shen, M. R. Ware, Xijie Wang, T. J. Martínez, Thomas J. A. Wolf Oct 2021

Conformer-Specific Photochemistry Imaged In Real Space And Time, E. G. Champenois, D. M. Sanchez, J. Yang, J. P. Figueira Nunes, A. Attar, Martin Centurion, R. Forbes, M. Gühr, K. Hegazy, F. Ji, S. K. Saha, Y. Liu, M. F. Lin, D. Luo, B. Moore, X. Shen, M. R. Ware, Xijie Wang, T. J. Martínez, Thomas J. A. Wolf

Martin Centurion Publications

Conformational isomers (conformers) of molecules play a decisive role in biology and organic chemistry. However, experimental methods for investigating chemical reaction dynamics are typically not conformersensitive. We report on a gas-phase megaelectronvolt ultrafast electron diffraction investigation of a-phellandrene undergoing an electrocyclic ring-opening reaction. We directly imaged the evolution of a specific set of a-phellandrene conformers into the product isomer predicted by the Woodward-Hoffmann rules in real space and time. Our experimental results are in quantitative agreement with nonadiabatic quantum molecular dynamics simulations, which provide considerable detail of how conformation influences the time scale and quantum efficiency of photoinduced ring-opening reactions. …


Magnetic Field Perturbations To A Soft X-Ray-Activated Fe (Ii) Molecular Spin State Transition, Guanhua Hao, Alpha T. N’Diaye, Thilini K. Ekanayaka, Ashley S. Dale, Xuanyuan Jiang, Esha Mishra, Corbyn Mellinger, Saeed Yazdani, John W. Freeland, Jian Zhang, Ruihua Cheng, Xiaoshan Xu, Peter Dowben Oct 2021

Magnetic Field Perturbations To A Soft X-Ray-Activated Fe (Ii) Molecular Spin State Transition, Guanhua Hao, Alpha T. N’Diaye, Thilini K. Ekanayaka, Ashley S. Dale, Xuanyuan Jiang, Esha Mishra, Corbyn Mellinger, Saeed Yazdani, John W. Freeland, Jian Zhang, Ruihua Cheng, Xiaoshan Xu, Peter Dowben

Peter Dowben Publications

The X-ray-induced spin crossover transition of an Fe (II) molecular thin film in the presence and absence of a magnetic field has been investigated. The thermal activation energy barrier in the soft X-ray activation of the spin crossover transition for [Fe{H2B(pz)2 }2 (bipy)] molecular thin films is reduced in the presence of an applied magnetic field, as measured through X-ray absorption spectroscopy at various temperatures. The influence of a 1.8 T magnetic field is sufficient to cause deviations from the expected exponential spin state transition behavior which is measured in the field free case. We find …


Giant Transport Anisotropy In Res2 Revealed Via Nanoscale Conducting-Path Control, Dawei Li, Shuo Sun, Jingfeng Song, Ding-Fu Shao, Evgeny Y. Tsymbal, Stephen Ducharme, Xia Hong Sep 2021

Giant Transport Anisotropy In Res2 Revealed Via Nanoscale Conducting-Path Control, Dawei Li, Shuo Sun, Jingfeng Song, Ding-Fu Shao, Evgeny Y. Tsymbal, Stephen Ducharme, Xia Hong

Stephen Ducharme Publications

The low in-plane symmetry in layered 1T’-ReS2 results in strong band anisotropy, while its manifestation in the electronic properties is challenging to resolve due to the lack of effective approaches for controlling the local current path. In this work, we reveal the giant transport anisotropy in monolayer to four-layer ReS2 by creating directional conducting paths via nanoscale ferroelectric control. By reversing the polarization of a ferroelectric polymer top layer, we induce a conductivity switching ratio of >1.5 × 108 in the ReS2 channel at 300 K. Characterizing the domain-defined conducting nanowires in an insulating background shows that the …


Spontaneous Fluctuations In A Magnetic Fe/Gd Skyrmion Lattice, M. H. Seaberg, B. Holladay, S. A. Montoya, X. Y. Zheng, J. C.T. Lee, A. H. Reid, J. D. Koralek, L. Shen, V. Esposito, G. Coslovich, P. Walter, S. Zohar, V. Thampy, M. F. Lin, P. Hart, K. Nakahara, R. Streubel, S. D. Kevan, P. Fischer, W. Colocho, A. Lutman, F. J. Decker, E. E. Fullerton, M. Dunne, S. Roy, S. K. Sinha, J. J. Turner Sep 2021

Spontaneous Fluctuations In A Magnetic Fe/Gd Skyrmion Lattice, M. H. Seaberg, B. Holladay, S. A. Montoya, X. Y. Zheng, J. C.T. Lee, A. H. Reid, J. D. Koralek, L. Shen, V. Esposito, G. Coslovich, P. Walter, S. Zohar, V. Thampy, M. F. Lin, P. Hart, K. Nakahara, R. Streubel, S. D. Kevan, P. Fischer, W. Colocho, A. Lutman, F. J. Decker, E. E. Fullerton, M. Dunne, S. Roy, S. K. Sinha, J. J. Turner

Robert Streubel Papers

Magnetic skyrmions are topological spin textures that exhibit classical or quantum quasiparticle behavior. A substantial amount of research has occurred in this field, both because of their unique electromagnetic properties and potential application for future nonvolatile memory storage applications, as well as fundamental questions on their topology and unique magnetic phases. Here, we investigate the fluctuation properties of a magnetic Fe/Gd skyrmion lattice, using short-pulsed x rays. We first measure spontaneous fluctuations of the skyrmion lattice phase and find an inherent, collective mode showing an underdamped oscillation with a relaxation of a couple of nanoseconds. Further observations track the response …


High Sensitivity Multi-Axes Rotation Sensing Using Large Momentum Transfer Point Source Atom Interferometry, Jinyang Li, Gregório R. M. Da Silva, Wayne Cheng-Wei Huang, Mohamed Fouda, Jason Bonacum, Timothy L. Kovachy, Selim M. Shahriar Aug 2021

High Sensitivity Multi-Axes Rotation Sensing Using Large Momentum Transfer Point Source Atom Interferometry, Jinyang Li, Gregório R. M. Da Silva, Wayne Cheng-Wei Huang, Mohamed Fouda, Jason Bonacum, Timothy L. Kovachy, Selim M. Shahriar

Department of Physics and Astronomy: Faculty Publications

A point source interferometer (PSI) is a device where atoms are split and recombined by applying a temporal sequence of Raman pulses during the expansion of a cloud of cold atoms behaving approximately as a point source. The PSI can work as a sensitive multi-axes gyroscope that can automatically filter out the signal from accelerations. The phase shift arising from the rotations is proportional to the momentum transferred to each atom from the Raman pulses. Therefore, by increasing the momentum transfer, it should be possible to enhance the sensitivity of the PSI. Here, we investigate the degree of enhancement in …


Kapitza-Dirac Blockade: A Universal Tool For The Deterministic Preparation Of Non-Gaussian Oscillator States, Wayne Cheng-Wei Huang, Herman Batelaan, Markus Arndt Jun 2021

Kapitza-Dirac Blockade: A Universal Tool For The Deterministic Preparation Of Non-Gaussian Oscillator States, Wayne Cheng-Wei Huang, Herman Batelaan, Markus Arndt

Department of Physics and Astronomy: Faculty Publications

Harmonic oscillators count among the most fundamental quantum systems with important applications in molecular physics, nanoparticle trapping, and quantum information processing. Their equidistant energy level spacing is often a desired feature, but at the same time a challenge if the goal is to deterministically populate specific eigenstates. Here, we show how interference in the transition amplitudes in a bichromatic laser field can suppress the sequential climbing of harmonic oscillator states (Kapitza-Dirac blockade) and achieve selective excitation of energy eigenstates, cat states, and other non-Gaussian states. This technique can transform the harmonic oscillator into a coherent two-level system or be used …


Publications Of Paul D. Burrow, Paul Burrow Jun 2021

Publications Of Paul D. Burrow, Paul Burrow

Paul Burrow Publications

A chronological list of 111 publications (1967-2014), with links to public access copies of 50 or more in the UNL Digital Commons. Updated as of 6/18/2021.


Corrigendum: Surface Termination And Schottky-Barrier Formation Of In4Se3(001) [Semiconductor Science And Technology (2020) 35 (065009) Doi: 10.1088/1361-6641/Ab7e45], Archit Dhingra, Pavlo V. Galiy, Lu Wang, Nataliia S. Vorobeva, Alexey Lipatov, Angel Torres, Taras M. Nenchuk, Simeon J. Gilbert, Alexander Sinitskii, Andrew J. Yost, Wai-Ning Mei, Keisuke Fukutani, Jia Shiang Chen, Peter Dowben Jun 2021

Corrigendum: Surface Termination And Schottky-Barrier Formation Of In4Se3(001) [Semiconductor Science And Technology (2020) 35 (065009) Doi: 10.1088/1361-6641/Ab7e45], Archit Dhingra, Pavlo V. Galiy, Lu Wang, Nataliia S. Vorobeva, Alexey Lipatov, Angel Torres, Taras M. Nenchuk, Simeon J. Gilbert, Alexander Sinitskii, Andrew J. Yost, Wai-Ning Mei, Keisuke Fukutani, Jia Shiang Chen, Peter Dowben

Peter Dowben Publications

Through the description of various surface terminations, the chain direction of In4Se3 in this paper [1] is implied to be in the plane of its surface. Even though the common convention for photoemission spectroscopy is to place z-axis along the surface normal, the axis perpendicular to the growth direction for this indium selenide is the crystallographic a-axis (and not the c-axis) [2–4]. Therefore, in our work the surface of In4Se3 should have been labeled (100), and not (001), to prevent any confusion that may have resulted from a less than conventional index notation. Data availability statement The data that support …


Colossal Intrinsic Exchange Bias From Interfacial Reconstruction In Epitaxial Cofe2 O4/Al2 O3 Thin Films, Detian Yang, Yu Yun, Arjun Subedi, Nicholas E. Rogers, David M. Cornelison, Peter Dowben, Xiaoshan Xu Jun 2021

Colossal Intrinsic Exchange Bias From Interfacial Reconstruction In Epitaxial Cofe2 O4/Al2 O3 Thin Films, Detian Yang, Yu Yun, Arjun Subedi, Nicholas E. Rogers, David M. Cornelison, Peter Dowben, Xiaoshan Xu

Peter Dowben Publications

We have studied the epitaxial CoFe2O4 (111) films grown on Al2O3 (0001) substrates of different thickness at various temperature and discovered colossal intrinsic exchange bias up to 7 ± 2 kOe. X-ray and electron diffraction clearly indicate an interfacial layer about 2 nm of different crystal structure from the “bulk” part of the CoFe2O4 film. The thickness dependence of the exchange bias suggests a hidden antiferromagnetic composition in the interfacial layer that couples to the ferrimagnetic “bulk” part of the CoFe2O4 film as the origin of the exchange …


Magnetism And Topological Hall Effect In Antiferromagnetic Ru2Mnsn-Based Heusler Compounds, Wenyong Zhang, Balamurugan Balasubramanian, Yang Sun, Ahsan Ullah, Ralph Skomski, Rabindra Pahari, Shah R. Valloppilly, Xingzhong Li, Cai-Zhuang Wang, Kai-Ming Ho, David J. Sellmyer May 2021

Magnetism And Topological Hall Effect In Antiferromagnetic Ru2Mnsn-Based Heusler Compounds, Wenyong Zhang, Balamurugan Balasubramanian, Yang Sun, Ahsan Ullah, Ralph Skomski, Rabindra Pahari, Shah R. Valloppilly, Xingzhong Li, Cai-Zhuang Wang, Kai-Ming Ho, David J. Sellmyer

Nebraska Center for Materials and Nanoscience: Faculty Publications

Heusler compounds and alloys based on them are of great recent interest because they exhibit a wide variety of spin structures, magnetic properties, and electron-transport phenomena. Their properties are tunable by alloying and we have investigated L21-ordered compound Ru2MnSn and its alloys by varying the atomic Mn:Sn composition. While antiferromagnetic ordering with a Néel temperature of 361 K was observed in Ru2MnSn, the Mn-poor Ru2Mn0.8Sn1.2 alloy exhibits properties of a diluted antiferromagnet in which there are localized regions of uncompensated Mn spins. Furthermore, a noncoplanar spin structure, evident from …


Voltage-Controlled Magnetic Anisotropy In Antiferromagnetic Mgo-Capped Mnpt Films, P. H. Chang, Wuzhang Fang, T. Ozaki, Kirill Belashchenko May 2021

Voltage-Controlled Magnetic Anisotropy In Antiferromagnetic Mgo-Capped Mnpt Films, P. H. Chang, Wuzhang Fang, T. Ozaki, Kirill Belashchenko

Kirill Belashchenko Publications

The magnetic anisotropy in MgO-capped MnPt films and its voltage control are studied using first-principles calculations. Sharp variation of the magnetic anisotropy with film thickness, especially in the Pt-terminated film, suggests that it may be widely tuned by adjusting the film thickness. In thick films the linear voltage control coefficient is as large as 1.5 and -0.6 pJ/Vm for Pt-terminated and Mn-terminated interfaces, respectively. The combination of a widely tunable magnetic anisotropy energy and a large voltage-control coefficient suggest that MgO-capped MnPt films can serve as a versatile platform for magnetic memory and antiferromagnonic applications.


Study Of Neon Collisional Negative Ion Compound Resonance Using A Trochoidal Electron Monochromator, Will Brunner Mar 2021

Study Of Neon Collisional Negative Ion Compound Resonance Using A Trochoidal Electron Monochromator, Will Brunner

Honors Theses

This thesis describes the experimental apparatus and procedure used to measure the excitation function of the 2p53p 3D3 state of neon. First I describe the effect on this excitation of negative ion resonances and previous experiments to measure the excitation function, as well as suggestions for future applications of such studies. Then the experimental apparatus is described in three parts. The vacuum system uses a turbomolecular pump to decrease the pressure of the chamber to as low as 4*10-9 Torr. The electron beam system incorporates a trochoidal electron monochromator to send a highly monochromatic beam …


Correction To "Quantitative Study Of The Energy Changes In Voltage-Controlled Spin Crossover Molecular Thin Films" [The Journal Of Physical Chemistry Letters (2020) 11:19 (8231-8237) Doi: 10.1021/Acs.Jpclett.0c02209], Aaron Mosey, Ashley S. Dale, Guanhua Hao, Alpha N'Diaye, Peter Dowben, Ruihua Cheng Mar 2021

Correction To "Quantitative Study Of The Energy Changes In Voltage-Controlled Spin Crossover Molecular Thin Films" [The Journal Of Physical Chemistry Letters (2020) 11:19 (8231-8237) Doi: 10.1021/Acs.Jpclett.0c02209], Aaron Mosey, Ashley S. Dale, Guanhua Hao, Alpha N'Diaye, Peter Dowben, Ruihua Cheng

Peter Dowben Publications

In our recent publication, Figure 5 was published without adequate due diligence. The correct TOC Abstract graphic and Figure 5 are contained here in this correction. The correct on to off current ratios are in the range of 4 to 5, not 100 and the signal to noise ratios are far less than previously shown.


Electron Beam Dispersion Compensator Using A Wien Filter, Jackson Lederer Mar 2021

Electron Beam Dispersion Compensator Using A Wien Filter, Jackson Lederer

Honors Theses

When an electron beam travels through space, it spreads out over time which impedes the ability to work with short electron pulses in the lab. A Wien filter is a device consisting of perpendicular electric and magnetic fields which filters charged particles based on their velocities. For a specific velocity, the two forces from the two fields in the filter cancel each other out letting charges with that velocity travel straight through the filter. Charges moving at other speeds are deflected as they have a net force applied to them from the filter. If a particle is deflected from the …


Nonvolatile Voltage Controlled Molecular Spin‐State Switching For Memory Applications, Thilini K. Ekanayaka, Guanhua Hao, Aaron Mosey, Ashley S. Dale, Xuanyuan Jiang, Andrew J. Yost, Keshab R. Sapkota, George T. Wang, Jian Zhang, Alpha T. N’Diaye, Andrew Marshall, Ruihua Cheng, Azad Naeemi, Xiaoshan Xu, Peter Dowben Mar 2021

Nonvolatile Voltage Controlled Molecular Spin‐State Switching For Memory Applications, Thilini K. Ekanayaka, Guanhua Hao, Aaron Mosey, Ashley S. Dale, Xuanyuan Jiang, Andrew J. Yost, Keshab R. Sapkota, George T. Wang, Jian Zhang, Alpha T. N’Diaye, Andrew Marshall, Ruihua Cheng, Azad Naeemi, Xiaoshan Xu, Peter Dowben

Peter Dowben Publications

Nonvolatile, molecular multiferroic devices have now been demonstrated, but it is worth giving some consideration to the issue of whether such devices could be a competitive alternative for solid-state nonvolatile memory. For the Fe (II) spin crossover complex [Fe{H2B(pz)2}2(bipy)], where pz = tris(pyrazol-1-yl)-borohydride and bipy = 2,20-bipyridine, voltage-controlled isothermal changes in the electronic structure and spin state have been demonstrated and are accompanied by changes in conductance. Higher conductance is seen with [Fe{H2B(pz)2}2(bipy)] in the high spin state, while lower conductance occurs for the low spin state. Plausibly, …


Remote Mesoscopic Signatures Of Induced Magnetic Texture In Graphene, N. Arabchigavkani, R. Somphonsane, H. Ramamoorthy, G. He, J. Nathawat, S. Yin, B. Barut, K. He, M. D. Randle, R. Dixit, K. Sakanashi, N. Aoki, K. Zhang, L. Wang, W. N. Mei, Peter Dowben, J. Fransson, J. P. Bird Feb 2021

Remote Mesoscopic Signatures Of Induced Magnetic Texture In Graphene, N. Arabchigavkani, R. Somphonsane, H. Ramamoorthy, G. He, J. Nathawat, S. Yin, B. Barut, K. He, M. D. Randle, R. Dixit, K. Sakanashi, N. Aoki, K. Zhang, L. Wang, W. N. Mei, Peter Dowben, J. Fransson, J. P. Bird

Peter Dowben Publications

Mesoscopic conductance fluctuations are a ubiquitous signature of phase-coherent transport in small conductors, exhibiting universal character independent of system details. In this Letter, however, we demonstrate a pronounced breakdown of this universality, due to the interplay of local and remote phenomena in transport. Our experiments are performed in a graphene-based interaction-detection geometry, in which an artificial magnetic texture is induced in the graphene layer by covering a portion of it with a micromagnet. When probing conduction at some distance from this region, the strong influence of remote factors is manifested through the appearance of giant conductance fluctuations, with amplitude much …


Plasmonic Waveguides To Enhance Quantum Electrodynamic Phenomena At The Nanoscale, Ying Li, Christos Argyropoulos Feb 2021

Plasmonic Waveguides To Enhance Quantum Electrodynamic Phenomena At The Nanoscale, Ying Li, Christos Argyropoulos

Department of Electrical and Computer Engineering: Faculty Publications

The emerging field of plasmonics can lead to enhanced light-matter interactions at extremely nanoscale regions. Plasmonic (metallic) devices promise to efficiently control both classical and quantum properties of light. Plasmonic waveguides are usually used to excite confined electromagnetic modes at the nanoscale that can strongly interact with matter. The analysis of these nanowaveguides exhibits similarities with their low frequency microwave counterparts. In this article, we review ways to study plasmonic nanostructures coupled to quantum optical emitters from a classical electromagnetic perspective. These quantum emitters are mainly used to generate single-photon quantum light that can be employed as a quantum bit …


Chiral Spin Textures In Amorphous Iron–Germanium Thick Films, Robert Streubel, D. Simca Bouma, Frank Bruni, Xiaoqian Chen, Peter Ercius, Jim Ciston, Alpha T. N'Diaye, Sujoy Roy, Steve D. Kevan, Peter Fischer, Frances Hellman Feb 2021

Chiral Spin Textures In Amorphous Iron–Germanium Thick Films, Robert Streubel, D. Simca Bouma, Frank Bruni, Xiaoqian Chen, Peter Ercius, Jim Ciston, Alpha T. N'Diaye, Sujoy Roy, Steve D. Kevan, Peter Fischer, Frances Hellman

Robert Streubel Papers

Topological solitary fields, such as magnetic and polar skyrmions, are envisioned to revolutionize microelectronics. These configurations have been stabilized in solid-state materials with a global inversion symmetry breaking, which translates in magnetic materials into a vector spin exchange known as the Dzyaloshinskii–Moriya interaction (DMI), as well as spin chirality selection and isotropic solitons. This work reports experimental evidence of 3D chiral spin textures, such as helical spins and skyrmions with different chirality and topological charge, stabilized in amorphous Fe–Ge thick films. These results demonstrate that structurally and chemically disordered materials with a random DMI can resemble inversion symmetry broken systems …


Structure Retrieval In Liquid-Phase Electron Scattering, Jie Yang, J. Pedro F. Nunes, Kathryn Ledbetter, Elisa Biasin, Martin Centurion, Zhijiang Chen, Amy A. Cordones, Christopher Crissman, Daniel P. Deponte, Siegfried H. Glenzer, Ming Fu Lin, Mianzhen Mo, Conor D. Rankine, Xiaozhe Shen, Thomas J.A. Wolf, Xijie Wang Jan 2021

Structure Retrieval In Liquid-Phase Electron Scattering, Jie Yang, J. Pedro F. Nunes, Kathryn Ledbetter, Elisa Biasin, Martin Centurion, Zhijiang Chen, Amy A. Cordones, Christopher Crissman, Daniel P. Deponte, Siegfried H. Glenzer, Ming Fu Lin, Mianzhen Mo, Conor D. Rankine, Xiaozhe Shen, Thomas J.A. Wolf, Xijie Wang

Martin Centurion Publications

Electron scattering on liquid samples has been enabled recently by the development of ultrathin liquid sheet technologies. The data treatment of liquid-phase electron scattering has been mostly reliant on methodologies developed for gas electron diffraction, in which theoretical inputs and empirical fittings are often needed to account for the atomic form factor and remove the inelastic scattering background. In this work, we present an alternative data treatment method that is able to retrieve the radial distribution of all the charged particle pairs without the need of either theoretical inputs or empirical fittings. The merits of this new method are illustrated …


Temporal Coherent Control Of Resonant Two-Photon Double Ionization Of The Hydrogen Molecule Via Doubly Excited States, Jean Marcel Ngoko Djiokap, Anthony F. Starace Jan 2021

Temporal Coherent Control Of Resonant Two-Photon Double Ionization Of The Hydrogen Molecule Via Doubly Excited States, Jean Marcel Ngoko Djiokap, Anthony F. Starace

Anthony F. Starace Publications

We use time-delayed, counter-rotating, circularly polarized few-cycle attosecond nonoverlapping pulses to study the temporal coherent control of the resonant process of two-photon double ionization (TPDI) of hydrogen molecule via doubly excited states for pulse propagation direction along ˆk either parallel or perpendicular to the molecular axis ˆR. For ˆk ‖ ˆR and a pulse carrier frequency of 36 eV resonantly populating the Q2 1∏ + u (1) doubly excited state as well as other 1∏ + u doubly excited states, we find that the indirect ionization pathway through these doubly excited states changes the character of the kinematical vortex-shaped …


Magnetism In Curved Geometries, Robert Streubel, Evgeny Y. Tsymbal, Peter Fischer Jan 2021

Magnetism In Curved Geometries, Robert Streubel, Evgeny Y. Tsymbal, Peter Fischer

Robert Streubel Papers

Curvature impacts physical properties across multiple length scales, ranging from the macroscopic scale, where the shape and size vary drastically with the curvature, to the nanoscale at interfaces and inhomogeneities in materials with structural, chemical, electronic, and magnetic short-range order. In quantum materials, where correlations, entanglement, and topology dominate, the curvature opens the path to novel characteristics and phenomena that have recently emerged and could have a dramatic impact on future fundamental and applied studies of materials. Particularly, magnetic systems hosting non-collinear and topological states and 3D magnetic nanostructures strongly benefit from treating curvature as a new design parameter to …