Article
Physics, Multidisciplinary
Henrik Parsamyan, Torgom Yezekyan, Khachatur Nerkararyan, Sergey Bozhevolnyi
Summary: Scanning near-field optical microscopy (SNOM) is a powerful optical technique for visualizing surface nanostructures and fields beyond the diffraction limit. The resolution of SNOM is theoretically unlimited but limited in practice due to background light scattering. This article proposes using a "dark" SNOM probe to suppress background scattering and improve sensitivity and resolution for nano-optical characterization.
NEW JOURNAL OF PHYSICS
(2023)
Article
Chemistry, Physical
G. Flores-Rangel, L. F. Lastras-Martinez, R. Castro-Garcia, O. Ruiz-Cigarrillo, R. E. Balderas-Navarro, L. D. Espinosa-Cuellar, A. Lastras-Martinez, J. M. J. Lopes
Summary: Graphene nanoribbons (GNRs) are unique structures with interesting optical and electronic properties that have great potential in optoelectronics and nanoelectronics. Utilizing a differential reflectance contrast (DRC) technique can accurately evaluate the thickness and uniformity of GNRs. Studying GNRs on SiC substrates provides a promising method for the development of graphene-based nanoelectronics.
APPLIED SURFACE SCIENCE
(2021)
Article
Nanoscience & Nanotechnology
Kiin Nam, Hyuntae Kim, Woongkyu Park, Jae Sung Ahn, Soobong Choi
Summary: Scanning thermal microscopy (SThM) allows for the measurement of thermal characteristic information from signals obtained by scanning a thermometer probe over a sample surface. In this study, SThM is used to generate sub-wavelength near-field optical images in a plasmonic grating coupler, and it is shown that the dominant component of the SThM signal is from the optical response rather than the thermal response.
Article
Chemistry, Multidisciplinary
Po-Wen Tang, Shiue-Yuan Shiau, He-Chun Chou, Xin-Quan Zhang, Jia-Ru Yu, Chun-Te Sung, Yi-Hsien Lee, Chi Chen
Summary: Beyond-diffraction-limit optical absorption spectroscopy provides detailed information on the band structures of 2D materials, and near-field broadband absorption microscopy allows visualization and analysis of their spatially varying band structures.
Article
Materials Science, Multidisciplinary
Yu E. Vysokikh, T. Mikhailova, S. Yu Krasnoborodko, A. S. Kolomiytsev, O. I. Ilin, A. N. Shaposhnikov, V. N. Berzhansky, M. F. Bulatov, D. Churikov, V. Shevyakov
Summary: The study discusses the importance of improving magnetic structure investigation with the lowest possible resolution for the study and practical implementation of fundamental magnetism. By using scanning near-field magneto-optical microscopy (SNMOM) and new technology based on focused ion beam (FIB) treatment to produce aperture cantilevers with carbon hollow pyramid tip (ACCT), it is shown that ACCT have better light transmission coefficients compared to commonly used aperture silicon cantilevers.
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
(2021)
Article
Chemistry, Multidisciplinary
Xinzhong Chen, Suheng Xu, Sara Shabani, Yueqi Zhao, Matthew Fu, Andrew J. Millis, Michael M. Fogler, Abhay N. Pasupathy, Mengkun Liu, D. N. Basov
Summary: The ability to perform nanometer-scale optical imaging and spectroscopy is crucial for decoding low-energy effects in quantum materials, as well as identifying vibrational fingerprints in planetary and extraterrestrial particles, catalytic substances, and aqueous biological samples. The scattering-type scanning near-field optical microscopy (s-SNOM) technique, along with artificial intelligence (AI) and machine learning (ML) algorithms, can greatly enhance the efficiency, accuracy, and intelligence of scanning probe optical nanoscopy.
ADVANCED MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Zhaomin Peng, Dehai Zhang, Shuqi Ge, Jin Meng
Summary: In this study, a finite element model (FEM) is proposed to quantify the near-field interactions, and to investigate the edge effect and antenna effect in THz s-SNOM. Our results indicate that the proposed model can give us a better understanding of the near-field interactions and direct the parameter design of the probe for THz s-SNOM.
APPLIED SCIENCES-BASEL
(2023)
Article
Nanoscience & Nanotechnology
Binbin Wang, Sera Kim, Tingting Zhai, Jinbong Seok, Heejun Yang, Rafael Salas-Montiel
Summary: The paper demonstrates the dielectric screening by hBN in graphene integrated on a silicon photonic waveguide using NSOM and Raman spectroscopy. It confirms the better performance of hBN compared to SiO2 in terms of lower electric field slope and scattering rate in graphene.
Article
Anatomy & Morphology
Melissa Matrecitos-Avila, Remy Avila, Reinher Pimentel-Dominguez, Salvador Cuevas, Elisa Tamariz, Pablo Loza-Alvarez
Summary: Precise and stable focus is crucial in confocal microscopy to ensure image sharpness and prevent misinterpretation of radiometric fluctuations as variations in fluorescence intensity. This study reports a focus drift caused by a continuous wave laser of 810-nm wavelength introduced along the optical path of an inverted confocal microscope. The drift is observed when the laser is turned on or off, with the focus position shifting towards lower or higher values of the vertical coordinate z, respectively. Analysis suggests that the focus drift is due to heating of the immersion oil.
MICROSCOPY RESEARCH AND TECHNIQUE
(2022)
Article
Microscopy
Sara Backtiari, Mahdi Sovizi
Summary: This paper introduces a method called near-field scanning optical microscopy (NSOM) to overcome the diffraction limit using sub-wavelength apertures. By simulating the near field in the vicinity of three-dimensional nano-optical apertureless probes, the effects of different parameters on the generated near field are studied.
Article
Chemistry, Multidisciplinary
Julian Barnett, Lukas Wehmeier, Andreas Hessler, Martin Lewin, Julian Pries, Matthias Wuttig, J. Michael Klopf, Susanne C. Kehr, Lukas M. Eng, Thomas Taubner
Summary: Chalcogenide phase change materials can reversibly switch between non-volatile states with vastly different optical properties, enabling novel active nanophotonic devices. In this study, infrared scattering-type scanning near-field optical microscopy (SNOM) and Kelvin probe force microscopy (KPFM) were used to investigate four states of laser-switched Ge3Sb2Te6 with nanometer lateral resolution. The research found that SNOM is sensitive to differences between crystalline and amorphous states, while KPFM has higher sensitivity to changes introduced by melt-quenching.
Review
Chemistry, Multidisciplinary
Mohammad Kamal Hossain
Summary: The exploitation of optical confinement in the nanoscale provides valuable information about the properties of materials. Near-field scanning optical microscopy (NSOM) is a technique that overcomes the diffraction limitation of traditional microscopy and spectroscopic techniques by using a near-field probe. In this Personal Account, the authors demonstrate the use of aperture NSOM (a-NSOM) to investigate optical confinement in various nanostructures, including dimers, nano-assemblies, and two-dimensional assemblies. The experimental observations are supported by finite-difference time-domain simulations. The ability to observe nanometric topography and surface-sensitive spectroscopic signals in the nanoscale not only advances our understanding of optical confinements in the near-field but also has implications for designing miniaturized and efficient systems.
Article
Chemistry, Multidisciplinary
Daniel J. Rizzo, Sara Shabani, Bjarke S. Jessen, Jin Zhang, Alexander S. McLeod, Carmen Rubio-Verdu, Francesco L. Ruta, Matthew Cothrine, Jiaqiang Yan, David G. Mandrus, Stephen E. Nagler, Angel Rubio, James C. Hone, Cory R. Dean, Abhay N. Pasupathy, D. N. Basov
Summary: The researchers successfully created nanometer-scale lateral p-n junctions using graphene/alpha-RuCl3 heterostructure near graphene nanobubbles. Through STM/STS and s-SNOM techniques, they investigated the electronic and optical responses of nanobubble p-n junctions, achieving p-n junctions with a width of around 3 nm and an electric field of approximately 10(8) V/m. The study also utilized ab initio density functional theory calculations to corroborate experimental data and provide insights into charge transfer mechanisms in 2D materials.
Article
Materials Science, Multidisciplinary
An-An Liu, Lei Wang, Jun Liu
Summary: This study developed a novel optical secondary storage memory operated in the near-infrared region by optimizing the optical coefficients of the probe composite and storage media. The device showed high optical transmittance and energy-saving features, with theoretical feasibility of achieving high data transfer rates and low energy consumption per bit.
PHYSICA STATUS SOLIDI-RAPID RESEARCH LETTERS
(2021)
Article
Chemistry, Multidisciplinary
Md. Sazzad Hossain, Adolfo I. B. Romo, Seth T. Putnam, Jahan Dawlaty, Veronica Augustyn, Joaquin Rodriguez-Lopez
Summary: Recently, non-Faradaic effects have been found to influence the electronic structure and reactivity of electrode-bound species. In this study, the near-electrode dissociation of N-heterocycle-BF3 Lewis adducts was investigated outside of the redox potential window. Through the use of scanning electrochemical microscopy and confocal fluorescence spectroscopy, a potential-dependent depletion of the adduct near the electrode was detected. This study suggests the presence of an electro-inductive effect on the N-heterocycle, and highlights the potential of electrostatics in field-driven electrocatalytic and electro-synthetic processes.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Nanoscience & Nanotechnology
Tarek Ali, David Lehninger, Maximilian Lederer, Songrui Li, Kati Kuhnel, Clemens Mart, Konstantin Mertens, Raik Hoffmann, Ricardo Olivo, Jennifer Emara, Kati Biedermann, Joachim Metzger, Robert Binder, Malte Czernohorsky, Thomas Kampfe, Johannes Muller, Konrad Seidel, Lukas M. Eng
Summary: The properties of hybrid ferroelectric and anti-ferroelectric films integrated in a single capacitor stack are reported. By adjusting the stack lamination and material type, the ferroelectric properties can be optimized, and the output ferroelectric hysteresis can be tailored by controlling the fraction of the anti-ferroelectric phase.
ADVANCED ELECTRONIC MATERIALS
(2022)
Article
Optics
M. Chen, T. V. A. G. de Oliveira, I. Ilyakov, T. Noerenberg, F. Kuschewski, J-C Deinert, N. Awari, A. Ponomaryov, M. Kuntzsch, S. C. Kehr, L. M. Eng, M. Gensch, S. Kovalev
Summary: This article presents a conceptually new approach to synchronizing accelerator-based light sources and external laser systems. The method utilizes an intense accelerator-based single-cycle terahertz pulse to slice a femtosecond-level part of a longer picosecond laser pulse, achieving precise synchronization of approximately 10 fs for real-time lock-in amplifier signal demodulation. The concept was successfully demonstrated in three benchmark experiments using a 4th generation accelerator-based terahertz light source.
Article
Materials Science, Multidisciplinary
Ayse Suenbuel, David Lehninger, Raik Hoffmann, Ricardo Olivo, Aditya Prabhu, Fred Schoene, Kati Kuehnel, Moritz Doellgast, Nora Haufe, Lisa Roy, Thomas Kaempfe, Konrad Seidel, Lukas M. Eng
Summary: This study investigates the influence of various thicknesses of hafnium-zirconium-oxide (HZO) in metal-ferroelectric-metal (MFM) capacitors on the reliability of ferroelectric devices under different operating temperatures and electric fields. The results show that the 7 nm thick HZO exhibits promising endurance and retention performance under high temperature and high load conditions, indicating potential applications.
ADVANCED ENGINEERING MATERIALS
(2023)
Article
Chemistry, Physical
Ankita De, Sattwick Haldar, Stefan Michel, Leonid Shupletsov, Volodymyr Bon, Nikolaj Lopatik, Lili Ding, Lukas M. Eng, Gunter K. Auernhammer, Eike Brunner, Andreas Schneemann
Summary: This study explores the tunability of covalent organic frameworks (COFs) and their processability. Anchoring alkoxy side chains to the COF backbone elongates the interlayer distance, leading to the successful exfoliation into nanosheets. The nanosheets show stability in dispersion, hydrophobic surface properties, and potential applications in lithium-ion battery separators.
CHEMISTRY OF MATERIALS
(2023)
Article
Physics, Applied
Kai J. Spychala, Zeeshan H. Amber, Lukas M. Eng, Michael Ruesing
Summary: Coherent nonlinear optical mu-spectroscopy is a powerful tool in material science, but interpreting the data can be challenging due to various effects. To simplify interpretation, this study presents an easy-to-use semi-analytical modeling approach based on Gaussian beams. The model successfully predicts nonlinear optical responses of optical materials, outperforming rigorous simulations in terms of computational time and system requirements.
JOURNAL OF APPLIED PHYSICS
(2023)
Article
Chemistry, Multidisciplinary
Flavio H. Feres, Ingrid D. Barcelos, Alisson R. Cadore, Lukas Wehmeier, Tobias Noerenberg, Rafael A. Mayer, Raul O. Freitas, Lukas M. Eng, Susanne C. Kehr, Francisco C. B. Maia
Summary: In this study, we used a highly brilliant and tunable free-electron laser to illuminate a nanoscope and observe the graphene nano-optical response from 1.5 to 6.0 THz. At frequencies below 2 THz, graphene exhibited a metal-like behavior and screened optical fields similar to noble metals. At 3.8 THz, plasmonic resonances caused a field-enhancement effect that improved the imaging power of graphene. Furthermore, we demonstrated tunability of the metallic behavior and the field-enhancement effect through electrical doping, providing additional control over graphene's nano-optical properties in the THz gap.
Article
Chemistry, Multidisciplinary
Jorg Schoepf, Arsha Thampi, Peter Milde, Dmytro Ivaneyko, Svitlana Kondovych, Denys Y. Kononenko, Lukas M. Eng, Lei Jin, Lin Yang, Lena Wysocki, Paul H. M. van Loosdrecht, Kornel Richter, Kostiantyn Yershov, Daniel Wolf, Axel Lubk, Ionela Lindfors-Vrejoiu
Summary: Ferromagnetic La0.7Sr0.3Mn1-xRuxO3 epitaxial multilayers with controlled variation of the Ru/Mn content were synthesized to investigate the possibility of generating a Dzyaloshinskii-Moriya interaction. Magnetic stripe domains separated by Neel-type domain walls and small Neel skyrmions were observed using magnetic force microscopy and Lorentz transmission electron microscopy. These findings are consistent with micromagnetic modeling, suggesting the existence of a sizable Dzyaloshinskii-Moriya interaction arising from inversion symmetry breaking and strain effects.
Article
Materials Science, Multidisciplinary
Ekta Singh, Mike N. Pionteck, Sven Reitzig, Michael Lange, Michael Ruesing, Lukas M. Eng, Simone Sanna
Summary: This paper analyzes the phonon frequencies of lithium niobate and lithium tantalate under uniaxial strain using density functional theory and mu-Raman spectroscopy. The majority of phonons show an increase in frequency under compressive strain, while the opposite is observed for tensile strains. Additionally, the lifting of degeneracy of E-type phonons is observed at moderate strain fields. This study allows for the systematic analysis of three-dimensional strains in devices assembled from lithium niobate and tantalate.
PHYSICAL REVIEW MATERIALS
(2023)
Article
Physics, Applied
M. Lederer, C. Mart, T. Kampfe, D. Lehninger, K. Seidel, M. Czernohorsky, W. Weinreich, B. Volkmann, L. M. Eng
Summary: The mechanism of nanoscopic domain switching in ferroelectric hafnium oxide and its implications for antiferroelectric-like behavior as well as for the wake-up effect are still under extensive discussion. Understanding this mechanism is crucial for numerous applications such as piezoelectric actuators, pyroelectric sensors, and nonvolatile memory devices. This article utilizes electrical and physical analysis methods to characterize ferroelectric hafnium oxide at both nanoscopic and macroscopic scales. Evidence of nanoscopic domains is observed through transmission Kikuchi diffraction, and combined with macroscopic Preisach density measurements, it is strongly suggested that antiferroelectric-like behavior and wake-up are governed by ferroelastic switching involving 90 degrees domain wall motion. Based on these findings, the material stack can be optimized to enhance microelectronic applications based on HfO2.
APPLIED PHYSICS LETTERS
(2023)
Article
Multidisciplinary Sciences
Joseph Matson, Soeren Wasserroth, Xiang Ni, Maximilian Obst, Katja Diaz-Granados, Giulia Carini, Enrico Maria Renzi, Emanuele Galiffi, Thomas G. Folland, Lukas M. Eng, J. Michael Klopf, Stefan Mastel, Sean Armster, Vincent Gambin, Martin Wolf, Susanne C. Kehr, Andrea Alu, Alexander Paarmann, Joshua D. Caldwell
Summary: The properties of phonon polaritons (PhPs) in the monoclinic crystal ss-Ga2O3 (bGO) were investigated, and strongly asymmetric propagation and frequency dispersive optical axis were observed. The symmetry-broken propagation of hyperbolic shear polaritons in bGO was directly imaged using scanning near-field optical microscopy (sSNOM). The control and enhancement of shear-induced propagation asymmetry were demonstrated by varying the incident laser orientation and polariton momentum using different sizes of nano-antennas, and significant rotation of the hyperbola axis was observed by changing the frequency of incident light. These findings lay the groundwork for the widespread utilization and implementation of polaritons in low-symmetry crystals.
NATURE COMMUNICATIONS
(2023)
Article
Chemistry, Multidisciplinary
Felix G. Kaps, Susanne C. Kehr, Lukas M. Eng
Summary: This paper theoretically and experimentally explores the influence of linear polarization control on near-field coupling, demonstrating that resonantly excited samples respond with a strong near-field signal to different linear polarization angles. By varying the illumination polarization angle, the scattered near-field signatures at different wavelengths can be quantitatively compared.
APPLIED SCIENCES-BASEL
(2023)
Article
Crystallography
Sergej Neufeld, Uwe Gerstmann, Laura Padberg, Christof Eigner, Gerhard Berth, Christine Silberhorn, Lukas M. Eng, Wolf Gero Schmidt, Michael Ruesing
Summary: This study calculated the phonon spectra of potassium titanyl phosphate and related compounds using density functional theory and compared them with experimental data, providing a more detailed assignment of spectral features. The findings improve the foundation for understanding the vibrational properties of the KTiOPO4 material family.
