Article
Chemistry, Multidisciplinary
Akhil Varri, Shabnam Taheriniya, Frank Brueckerhoff-Plueckelmann, Ivonne Bente, Nikolaos Farmakidis, Daniel Bernhardt, Harald Roesner, Maximilian Kruth, Achim Nadzeyka, Torsten Richter, Christopher David Wright, Harish Bhaskaran, Gerhard Wilde, Wolfram H. P. Pernice
Summary: This study demonstrates scalable and non-volatile photonic computational memories using automated silicon ion implantation. Precise spectral trimming of large-scale photonic ensembles is achieved with stability and minimal loss penalty. Spectrally aligned photonic memory and computing systems for general matrix multiplication are showcased, enabling wavelength multiplexed integrated architectures at large scales.
ADVANCED MATERIALS
(2023)
Article
Multidisciplinary Sciences
Sandhya Susarla, Pablo Garcia-Fernandez, Colin Ophus, Sujit Das, Pablo Aguado-Puente, Margaret McCarter, Peter Ercius, Lane W. Martin, Ramamoorthy Ramesh, Javier Junquera
Summary: This research utilizes a combination of techniques to probe the electronic structure within polar vortices in oxide superlattices at the atomic scale, finding that the peaks in Ti L-edge spectra systematically shift depending on the position of the Ti4+ cations. First-principles computations and simulations derived from first principles show good agreement with experimental results.
NATURE COMMUNICATIONS
(2021)
Article
Materials Science, Multidisciplinary
Rebecca B. B. Cummings, Matthew S. S. Blackmur, Mateusz Grunwald, Andrew Minty, Paul Styman, Ian MacLaren
Summary: The xenon content of a Zircaloy-4 thin film was quantified using high angle annular dark field (HAADF) images and DualEELS, and the results showed that the xenon had coalesced into bubbles. A semi-empirical standard was used for the quantification and the densities and pressures of the xenon bubbles were calculated.
JOURNAL OF NUCLEAR MATERIALS
(2022)
Article
Chemistry, Physical
B. P. E. Tee, M. Vos, H. Trombini, F. F. Selau, P. L. Grande, R. Thomaz
Summary: Polyvinyl chloride (PVC) rapidly decomposes when irradiated by charged particles. By using energy spectra of reflected electrons from PVC films, the relative amounts of Cl, C, and H present in the sample can be determined. The concentration of Cl decreases quickly during irradiation, while the density of electronic excitations produced under different irradiation conditions affects the Cl concentration as a function of fluence for electrons, protons, and He ions.
RADIATION PHYSICS AND CHEMISTRY
(2021)
Article
Chemistry, Multidisciplinary
Yuki Nomura, Kazuo Yamamoto, Yuji Yamagishi, Emiko Igaki
Summary: This study reveals the correlations between grain architecture, Li transport pathways, and phase transitions in Ni-rich layered cathodes using in situ transmission electron microscopy. The results show that Li ions are extracted through tortuous paths connecting the Li-containing a-b planes in the crystals, and the grain boundary resistance depends not only on the misorientations of the neighboring grains.
Article
Materials Science, Multidisciplinary
S. Hajati, K. Dashtian, M. Moradi, J. Toth, M. Keyhan
Summary: This study focuses on the surface analysis of Ni6MnO8 using reflection electron energy loss spectroscopy (REELS). The energy gap, energy loss functions, and optical parameters of Ni6MnO8 were determined using the REELS technique. Additionally, the inelastic mean free path of electrons in Ni6MnO8 and the surface excitation parameters were investigated.
Article
Chemistry, Physical
P. Roussel, K. S. Graham, S. C. Hernandez, J. J. Joyce, A. J. Nelson, R. Sykes, T. Venhaus, K. White
Summary: REELS were used to study Pu-Ga alloys, α-Pu2O3, and PuO2, with the Pu 6p excitation peaks serving as fingerprints. X-ray Photoelectron Spectroscopy aided in interpreting the REELS spectra, while the band gap of PuO2 was determined from the onset of energy loss. The data were evaluated using dielectric response theory, with comparisons made to previously reported results in the UV and EUV range.
APPLIED SURFACE SCIENCE
(2021)
Article
Chemistry, Physical
Mohan Kumar Kuntumalla, Gilad Gani, Miriam Fischer, Alon Hoffman
Summary: In this study, the sub-surface bonding, retention, and thermal stability of nitrogen in diamond (100) implanted with 200 and 800 eV N2+ at different temperatures were investigated. The results show that at room temperature and 600°C, nitrogen is mainly incorporated in the diamond lattice in a C-N/C=N bond configuration with a small C---N(nitrile-like) component for 200 eV N2+ implantation. For 800 eV N2+ implantation, nitrogen can occupy multiple bonding configurations including C-N/C=N and C---N bonds. Implantation at 600°C exhibited higher thermal stability of the implanted nitrogen due to defect curing and desorption of weakly bonded species.
SURFACES AND INTERFACES
(2023)
Article
Physics, Multidisciplinary
Tian-Long Li, Zheng Wei, Wei-Shi Wan
Summary: The newly designed correlative reflection electron microscopy (c-REM) integrates RHEED, EELS, and imaging, allowing for the simultaneous acquisition of structural, elemental, and spatial information of the same surface region with a spatial resolution of less than 50 nm. It is suitable for in-situ monitoring of the structural and chemical evolution of surfaces in advanced materials.
Article
Chemistry, Multidisciplinary
Hongbin Yang, Andrea Konecna, Xianghan Xu, Sang-Wook Cheong, Eric Garfunkel, F. Javier Garcia de Abajo, Philip E. Batson
Summary: This study demonstrates the existence of relatively long-lived plasmons supported by high-mobility charge carriers in La-doped BaSnO3. The properties of infrared localized surface plasmons in BLSO nanoparticles are systematically investigated using electron energy-loss spectroscopy. The results show that LSPs in BLSO exhibit a high degree of spatial confinement compared to noble metals, and have relatively low losses and high quality factors. Further analysis clarifies the relation between plasmon damping and carrier mobility in BLSO.
Article
Chemistry, Physical
Francisco Lagunas, Grant Alexander, Adriana Lee Punaro, Christian Moscosa, Linhua Hu, Jordi Cabana, Robert F. Klie
Summary: Mg batteries hold potential for high energy density rechargeable energy storage devices, but the lack of cathode materials that can efficiently de/insert Mg(2+) hinders their development. Despite promising predictions, experimental systems have not been able to compete with available Li-ion technologies. This highlights the need for fundamental studies on Mg electrochemistry.
ACS APPLIED ENERGY MATERIALS
(2023)
Review
Chemistry, Multidisciplinary
Kellie Jenkinson, Luis M. Liz-Marzan, Sara Bals
Summary: Electron tomography is an important technique for visualizing nanoparticle morphology. This article summarizes the experimental and computational development of various multimode tomography techniques and their role in overcoming materials science challenges. Current challenges and future directions of multimode tomography are also discussed.
ADVANCED MATERIALS
(2022)
Article
Multidisciplinary Sciences
Xiaoyan Li, Georg Haberfehlner, Ulrich Hohenester, Odile Stephan, Gerald Kothleitner, Mathieu Kociak
Summary: Surface phonon polaritons (SPhPs) are coupled photon-phonon excitations that strongly influence the optical and thermal behavior of nanomaterials. By using a scanning transmission electron microscope with a highly monochromated electron beam, varying SPhP signatures from nanoscale MgO cubes can be visualized and used to tomographically reconstruct the phononic surface electromagnetic fields of the object. This 3D information offers insights into nanoscale physical phenomena and is valuable for the design and optimization of nanostructures for new uses.
Article
Chemistry, Physical
Alice Apponi, Domenica Convertino, Neeraj Mishra, Camilla Coletti, Mauro Iodice, Franco Frasconi, Federico Pilo, Narcis Silviu Blaj, Daniele Paoloni, Ilaria Rago, Giovanni De Bellis, Gianluca Cavoto, Alessandro Ruocco
Summary: In this study, accurate transmission measurements of electrons below 1 keV through suspended monolayer graphene were reported. The monolayer graphene was grown using chemical vapor deposition and transferred onto transmission electron microscopy (TEM) grids. The transparency of graphene was obtained by measuring the direct beam current and transmitted current. The experimental results showed a transmission rate ranging from about 20% to about 80% for monolayer graphene within the experimental electron energy range. The high quality and grid coverage of the suspended graphene were confirmed through various characterization techniques. Additionally, evidence of suspended monolayer graphene was observed after annealing the samples in vacuum at 550 degrees C.
Article
Chemistry, Physical
David Garagnani, Paola De Padova, Carlo Ottaviani, Claudio Quaresima, Amanda Generosi, Barbara Paci, Bruno Olivieri, Mieczyslaw Jalochowski, Mariusz Krawiec
Summary: Si films of different thicknesses were grown on a Bi-covered Si substrate and studied using various surface characterization techniques. The results revealed the presence of a new Si allotrope structure, providing insights for the formation of heterostructures with topological insulator materials.
Article
Chemistry, Physical
R. Megginson, F. Grillo, S. M. Francis, V. Z. C. Paes, H. Trombini, P. L. Grande, A. K. Rossall, J. A. van den Berg, C. J. Baddeley
Summary: The behavior of bimetallic catalysts depends on the molar ratio of elements, nanoparticle size, and interaction with support material. This study investigates the properties of Cu and Au nanoparticles on CeO2 films using XPS and MEIS techniques, examining their changes under different annealing temperatures.
APPLIED SURFACE SCIENCE
(2022)
Article
Physics, Applied
Xinjun Liu, Peng Zhang, Shimul Kanti Nath, Shuai Li, Sanjoy Kumar Nandi, Robert Glen Elliman
Summary: A systematic analysis of negative differential resistance (NDR) modes in volatile memristors was conducted using a two-zone parallel model. The results identified the origin of different NDR responses and provided a strong basis for designing devices with complex NDR characteristics.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2022)
Article
Nanoscience & Nanotechnology
Sanjoy Kumar Nandi, Sujan Kumar Das, Yubo Cui, Assaad El Helou, Shimul Kanti Nath, Thomas Ratcliff, Peter Raad, Robert G. Elliman
Summary: This study investigates the thermal conductivity of amorphous NbOx films using timedomain thermoreflectance. The results show that the thermal conductivity varies with different film compositions and temperatures. Furthermore, the impact of these thermal conductivity variations on MOM devices is studied using a circuit model.
ACS APPLIED MATERIALS & INTERFACES
(2022)
Article
Engineering, Electrical & Electronic
Xiao-Yuan Wang, Chuan-Tao Dong, Peng-Fei Zhou, Sanjoy Kumar Nandi, Shimul Kanti Nath, Robert G. Elliman, Herbert Ho-Ching Iu, Sung-Mo Kang, Jason K. Eshraghian
Summary: This paper presents a design of multi-stage hybrid memristor-CMOS ternary combinational logic stages that are optimized for reducing silicon area occupation. Experimental results show an improvement in data density of each logic block by a factor of 5.2x to 17.3x.
IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS I-REGULAR PAPERS
(2022)
Article
Engineering, Electrical & Electronic
Yan Liang, Qian Zhu, Guangyi Wang, Shimul Kanti Nath, Herbert Ho-Ching Iu, Sanjoy Kumar Nandi, Robert Glen Elliman
Summary: Locally-active memristor (LAM) has potential applications in neuromorphic computing as an artificial neuron. Quantitative theoretical analysis on LAMs shows that their performance is closely associated with three crucial parameters: resistance, differential resistance, and a dynamic parameter. These parameters can be used to derive the small-signal equivalent circuit of LAMs and determine the oscillation frequency range and conditions for LAM-based oscillators.
IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS I-REGULAR PAPERS
(2022)
Article
Materials Science, Multidisciplinary
Won Jun Lee, Yusuff Adeyemi Salawu, Heon-Jung Kim, Chan Wook Jang, Sung Kim, Thomas Ratcliff, Robert G. Elliman, Zengji Yue, Xiaolin Wang, Sang-Eon Lee, Myung-Hwa Jung, Jong-Soo Rhyee, Suk-Ho Choi
Summary: Researchers have discovered a possible permanent phase transition from a Dirac semimetal to a Weyl semimetal in a single three-dimensional topological semimetal by ion implantation. The transition occurs when nonmagnetic gold ions are implanted, breaking the inversion symmetry of the material.
NPG ASIA MATERIALS
(2022)
Article
Nanoscience & Nanotechnology
Sanjoy Kumar Nandi, Etienne Puyoo, Shimul Kanti Nath, David Albertini, Nicolas Baboux, Sujan Kumar Das, Thomas Ratcliff, Robert G. Elliman
Summary: This study uses scanning thermal microscopy (SThM) as an alternative thermal mapping technique to map the temperature distribution in NbOx-based cross-bar and nanovia devices. The measurements reproduce the current redistribution and confinement processes previously observed by other techniques and demonstrate the high spatial resolution of SThM.
ACS APPLIED MATERIALS & INTERFACES
(2022)
Article
Chemistry, Physical
Rabin Majhi, Manoj K. Rajbhar, Pritam Das, Robert Glen Elliman, Shyamal Chatterjee
Summary: Ion irradiation of titanium oxide nanoparticles leads to the merging of nanoparticles and the formation of continuous chains. The irradiation also induces recrystallization and the formation of a new phase. Oxygen vacancies and surface defects are observed in the nanostructures. These changes affect the wettability and electrical conductivity of the material.
JOURNAL OF ALLOYS AND COMPOUNDS
(2022)
Article
Chemistry, Multidisciplinary
Sujan Kumar Das, Sanjoy Kumar Nandi, Camilo Verbel Marquez, Armando Rua, Mutsunori Uenuma, Etienne Puyoo, Shimul Kanti Nath, David Albertini, Nicolas Baboux, Teng Lu, Yun Liu, Tobias Haeger, Ralf Heiderhoff, Thomas Riedl, Thomas Ratcliff, Robert Glen Elliman
Summary: This study reports the structural, electrical, and thermal properties of V3O5 thin films and their application in metal/oxide/metal relaxation oscillators. The V3O5 devices exhibit electroforming-free threshold switching and stable negative differential resistance (NDR). The mechanisms underlying these characteristics are investigated, revealing confinement of conduction to a narrow filamentary path and temperature-dependent conductivity of the insulating phase. Additionally, the dynamics of individual and coupled V3O5-based oscillators are reported, demonstrating rich nonlinear dynamics. These findings establish V3O5 as a new functional material for volatile threshold switching and advance the development of solid-state neurons for neuromorphic computing.
ADVANCED MATERIALS
(2023)
Article
Physics, Applied
A. G. Salek, P. Y. Le, J. G. Partridge, T. J. Raeber, B. Haberl, R. Boehler, B. J. Murdoch, J. E. Bradby, T. Ratcliff, R. G. Elliman, D. R. McKenzie, D. G. McCulloch
Summary: Hydrogenated and deuterated amorphous carbon materials were synthesized with a density of 2.7 +/- 0.1 g/cm(3), indicating predominantly tetrahedral bonding. Minority sp(2) bonded atoms in hydrogen-free tetrahedral amorphous carbon could be passivated with hydrogen, similar to hydrogenated amorphous silicon. Neutron diffraction analysis confirmed the local bonding environment consistent with high density hydrogenated tetrahedral amorphous carbon and the tetrahedral molecular structure of neopentane. The optical bandgap of our material, 4.5 eV, closely matched the bandgap determined by scanning tunneling spectroscopy (4.3 eV), indicating successful passivation of sp(2) associated tail-states. The structural and electronic measurements supported a model where tetrahedrally bonded carbon regions are terminated by hydrogen, leading to hopping conductivity dominance.
APPLIED PHYSICS LETTERS
(2023)
Article
Optics
R. C. Fadanelli, P. L. Grande
Summary: In this study, the classical equations of motion and Poisson equation were solved self-consistently to calculate the electron-ion potential and ion stopping power for a projectile in a free-electron gas. The origin of the Barkas effect, which is responsible for the energy-loss difference between positively and negatively charged ions in the same target, was investigated. The effect is strongly enhanced by the multipolar part of the electron-ion potential and is partially related to the nonconservation of angular momentum in electron-ion collisions. These calculations were applied to understand the stopping of protons and antiprotons in aluminum at high energies.
Article
Chemistry, Multidisciplinary
Shimul Kanti Nath, Sanjoy Kumar Nandi, Sujan Kumar Das, Yan Liang, Robert G. Elliman
Summary: Volatile threshold switching and current-controlled negative differential resistance (NDR) in metal-oxide-metal (MOM) devices are influenced by the thermal properties of the device-structure. This study investigates the effect of metal electrodes on the threshold switching response of NbOx-based cross-point devices. The electroforming and switching characteristics are strongly influenced by the thickness and thermal conductivity of the top-electrode, affecting heat loss from the NbOx film.
Article
Materials Science, Multidisciplinary
L. F. S. Azeredo, J. Geshev, P. L. Grande, A. M. H. de Andrade
Summary: Distinct sharp peaks in the angular variations of in-plane major-loop remanent magnetization and coercivity, known as hard-axis collapse, were observed in several polycrystalline films. Recent research also discovered recoil-curve overshoot (RCO), where recoil magnetization branches lie outside the major loop, resulting in a significantly larger loop area. In this study, polycrystalline magnetron-sputtered Co films were subjected to Ne+ bombardment at different ion fluences in the presence of a magnetic field, leading to hard-axis collapse and RCO phenomena. Data analysis suggests that these phenomena are primarily caused by domain splitting when the measurement magnetic field is nearly perpendicular to the grain's easy axis.
Article
Chemistry, Inorganic & Nuclear
Joao V. B. Batista, Henrique Trombini, Andre Otsuka, Iury S. S. Silveira, Linda V. E. Caldas, Antonio O. O. de Souza, Adelmo S. S. Souza, Jorge L. O. Santos, Vinicius Coelho, Heveson Lima
Summary: Magnesium tetraborate (MgB4O7) is a material of interest in radiation dosimetry research. Challenges exist in advancing luminescence dosimetry, including the limited strategy of incorporating efficient dopants. The influence of lithium incorporation on the modification/suppression of the Optically Stimulated Luminescence (OSL)/Thermoluminescence (TL) signals of MgB4O7 is demonstrated. Lithium substitution leads to signal suppression by quenching certain centers and forming specific defects, while co-doping with lithium and cerium enhances luminescence and dosimetric properties.
DALTON TRANSACTIONS
(2023)
Article
Materials Science, Multidisciplinary
S. Lohmann, R. Holenak, P. L. Grande, D. Primetzhofer
Summary: We measured the energy-loss straggling of different ions in silicon using a transmission time-of-flight method. The straggling showed an increase with increasing ion velocities for channeled trajectories and for protons and helium in random geometry. However, for heavier ions, the electronic straggling did not decrease further but plateaued or even increased again at low velocities. Comparison with calculations showed that electronic stopping for light ions is dominated by electron-hole pair excitations, but for boron and silicon, local electron-promotion and charge-exchange events significantly contribute to energy loss at low velocities.
