Article
Nanoscience & Nanotechnology
Talieh S. Ghiasi, Alexey A. Kaverzin, Avalon H. Dismukes, Dennis K. de Wal, Xavier Roy, Bart J. van Wees
Summary: The coupling of bilayer graphene with the 2D interlayer antiferromagnetic CrSBr enables the active generation of spin currents in graphene, benefiting ultracompact spintronic devices. The strong spin-charge coupling in graphene and the high sensitivity of spin transport to the adjacent antiferromagnet's magnetization allow for the read-out of a single magnetic sublattice.
NATURE NANOTECHNOLOGY
(2021)
Article
Materials Science, Multidisciplinary
Hongyi Yan, Haiwen Liu
Summary: This study investigates the weak localization and weak antilocalization effects in twisted bilayer graphene on a hexagonal boron nitride substrate. The researchers discovered that interlayer scattering significantly contributes to the conductivity correction, and a double crossover from weak localization to weak antilocalization and back occurs at a specific range of Fermi energy.
Article
Physics, Multidisciplinary
Alexandre Jaoui, Ipsita Das, Giorgio Di Battista, Jaime Diez-Merida, Xiaobo Lu, Kenji Watanabe, Takashi Taniguchi, Hiroaki Ishizuka, Leonid Levitov, Dmitri K. Efetov
Summary: This study presents transport measurements in superconducting MATBG, where the correlated insulator states are suppressed by screening. The uninterrupted metallic ground state exhibits linear resistivity and Planckian scattering rates. A quantum-critical phase dominates the metallic ground state in a continuum of doping.
Article
Multidisciplinary Sciences
Na Xin, James Lourembam, Piranavan Kumaravadivel, A. E. Kazantsev, Zefei Wu, Ciaran Mullan, Julien Barrier, Alexandra A. Geim, I. V. Grigorieva, A. Mishchenko, A. Principi, V. I. Fal'ko, L. A. Ponomarenko, A. K. Geim, Alexey I. Berdyugin
Summary: The most distinctive feature of graphene is its electronic spectrum, in which the Dirac point is located. At low temperatures, the intrinsic behavior of this spectrum is often hidden by charge inhomogeneity, but thermal excitations can overcome the disorder at higher temperatures and create an electron-hole plasma. The behavior of this plasma in magnetic fields is not well understood at present.
Article
Materials Science, Multidisciplinary
Masahiro Kamada, Vanessa Gall, Jayanta Sarkar, Manohar Kumar, Antti Laitinen, Igor Gornyi, Pertti Hakonen
Summary: By measuring the magnetoresistance of suspended graphene in the Corbino geometry, we found strong relative magnetoresistance approaching 100% at high magnetic fields and weak temperature dependence at low temperatures. An increase in charge carrier density led to a decrease in relative magnetoresistance by half, and a shift in the position of the charge neutrality point was observed with increasing magnetic field. The gate dependence of the magnetoresistance allowed characterization of the role of scattering on different types of disorder and separation of bulk resistance from contact resistance, providing a more reliable method to extract bulk mobility.
Article
Physics, Multidisciplinary
Yanbang Chu, Le Liu, Yiru Ji, Jinpeng Tian, Fanfan Wu, Jian Tang, Yalong Yuan, Yanchong Zhao, Xiaozhou Zan, Rong Yang, Kenji Watanabe, Takashi Taniguchi, Dongxia Shi, Wei Yang, Guangyu Zhang
Summary: In this study, we report the magnetoresistance of metallic states in twisted double bilayer graphene (TDBG). Quadratic magnetoresistance is observed in both Moire valence band and Moire conduction band. The scaling analysis shows the validity of Kohler's rule in the Moire valence band, while the presence of quadratic magnetoresistance near the halo structure in the Moire conduction band violates Kohler's rule, demonstrating a different scaling related to band structure in TDBG. An alternative scaling near the halo structure is proposed. Further analysis suggests that the observed quadratic magnetoresistance and alternative scaling in the conduction band are related to the halo boundary.
Article
Materials Science, Multidisciplinary
Tom Westerhout, Mikhail Katsnelson, Malte Rosner
Summary: In this study, a material-realistic real-space many-body Hamiltonian for twisted bilayer graphene is derived from first principles. Plasmonic quantum dots with tunability are found in electron-doped twisted bilayer graphene supercells, and their similarity to electronic quantum dots is emphasized. The plasmonic quantum dot states are controlled by the system size, doping level, and twisting angle, and they form a versatile platform for tailored light-matter interactions.
Article
Physics, Multidisciplinary
Qianheng Du, Zhixiang Hu, Myung-Geun Han, Fernando Camino, Yimei Zhu, C. Petrovic
Summary: This study presents a comprehensive investigation on the anisotropy and out-of-plane electric transport in Fe3Sn2, a Kagome lattice material. The research reveals the presence of a large topological Hall effect along the c axis and the observation of angular magnetoresistance under different magnetic phases.
PHYSICAL REVIEW LETTERS
(2022)
Article
Multidisciplinary Sciences
Lihuan Sun, Louk Rademaker, Diego Mauro, Alessandro Scarfato, Arpad Pasztor, Ignacio Gutierrez-Lezama, Zhe Wang, Jose Martinez-Castro, Alberto F. Morpurgo, Christoph Renner
Summary: This study uses scanning tunneling microscopy to image backscattering in graphene/tungsten selenide heterostructures and quantitatively determine the strength of spin-orbit coupling (SOC). The results show that the strength of SOC is one order of magnitude larger than what theory predicted, but in agreement with previous transport experiments.
NATURE COMMUNICATIONS
(2023)
Article
Chemistry, Physical
Nathanael P. Kazmierczak, Madeline Van Winkle, Colin Ophus, Karen C. Bustillo, Stephen Carr, Hamish G. Brown, Jim Ciston, Takashi Taniguchi, Kenji Watanabe, D. Kwabena Bediako
Summary: Twisted bilayer graphene exhibits two-regime reconstruction mechanics based on twist angle, with applied heterostrain accumulating anisotropically in saddle-point regions to generate distinctive striped strain phases. Nanoscale spatial fluctuations in twist angle and uniaxial heterostrain were statistically evaluated, revealing the prevalence of short-range disorder in moire heterostructures. This study provides insights into the twist-angle-dependent electronic behavior and structural relaxation, disorder, and strain in moire materials.
Editorial Material
Nanoscience & Nanotechnology
Tatiana Latychevskaia
Summary: The topological parameters of the channel network in twisted bilayer graphene can be manipulated by intercalating lithium atoms.
NATURE NANOTECHNOLOGY
(2023)
Article
Physics, Condensed Matter
August Romeo, Hans Super
Summary: This study re-evaluates the first optimal or 'magic' angle leading to the nullity of the Dirac/Fermi velocity in twisted bilayer graphene and investigates the consequences when the properties of the two layers are not exactly the same. A moire combination of lattices without relative rotation but with different spacing lengths can also result in a vanishing Dirac velocity. Hopping amplitudes can vary, with curvature being one of the possible causes for their change. In cases of small curvature values and dominance of hopping energy scales, the optimal angle becomes wider compared to the 'flat' case.
JOURNAL OF PHYSICS-CONDENSED MATTER
(2023)
Article
Physics, Multidisciplinary
G. Liu, Xi-guang Wang, Z. Z. Luan, L. F. Zhou, S. Y. Xia, B. Yang, Y. Z. Tian, Guang-hua Guo, J. Du, D. Wu
Summary: The research team observed the unidirectional spin Hall magnetoresistance (USMR) in a heavy-metal-ferromagnetic-insulator bilayer, which is different from the established mechanisms in metallic bilayers. Through experiments and simulations, it was found that the USMR is attributed to the asymmetric magnon creation and annihilation induced by the spin-orbit torque.
PHYSICAL REVIEW LETTERS
(2021)
Article
Chemistry, Physical
Weiyi Lin, Pingping Zhuang
Summary: This study investigates the charge distribution in bilayer graphene and reveals that the hole distribution in the top and bottom layers of AB-BLG and t-BLG are similar, with the additional layer reducing the charge exchange at the graphene/dopant interface.
APPLIED SURFACE SCIENCE
(2022)
Article
Nanoscience & Nanotechnology
Alexander K. Fedotov, Uladzislaw E. Gumiennik, Julia A. Fedotova, Janusz Przewoznik, Czeslaw Kapusta
Summary: The study conducted an improved analysis of carrier transport in single-layer graphene and hybrid structures, showing the coexistence of negative and positive contributions in magnetoresistive effect. Various models were used to analyze the dependences on temperature and magnetic field, providing insights into the behavior of electrical resistance in the structures.
PHYSICA E-LOW-DIMENSIONAL SYSTEMS & NANOSTRUCTURES
(2024)
Article
Physics, Applied
Takuma Kobayashi, Maximilian Ruehl, Johannes Lehmeyer, Leonard K. S. Zimmermann, Michael Krieger, Heiko B. Weber
Summary: We studied the generation and transformation of intrinsic luminescent centers in 4H-polytype of silicon carbide through heavy ion implantation and subsequent annealing. Several unidentified luminescent features were observed and characterized under different temperatures and annealing conditions.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2022)
Article
Biochemical Research Methods
Navid Soltani, Elham Rabbany Esfahany, Sergey Druzhinin, Gregor Schulte, Julian Mueller, Benjamin Butz, Holger Schoenherr, Mario Agio, Nemanja Markesevic
Summary: In this study, we investigated a model bioassay in a liquid environment using a z-scanning planar Yagi-Uda antenna. We examined the fluorescence collection enhancement of ATTO-647N dye conjugated to DNA molecules and found that the antenna not only changed the excitation and decay rates, but also improved the emission pattern, resulting in a narrow emission angle and improved collection efficiency. Our method efficiently detected immobilized fluorescently-labeled DNA molecules, even at low concentrations. It is a versatile technique applicable to any immobilized, dye-labeled biomolecule in various environments.
BIOMEDICAL OPTICS EXPRESS
(2022)
Article
Materials Science, Multidisciplinary
Steven Schellert, Julian Mueller, Arne Ohrndorf, Bronslava Gorr, Benjamin Butz, Hans-Juergen Christ
Summary: This study investigates the isothermal and thermomechanical fatigue behavior of duplex stainless steel and correlates it with microstructural observations. The study reveals the differences in deformation modes and fatigue properties of the material at different temperatures.
Article
Physics, Multidisciplinary
Yuki Kobayashi, Christian Heide, Amalya C. Johnson, Vishal Tiwari, Fang Liu, David A. Reis, Tony F. Heinz, Shambhu Ghimire
Summary: Interactions between quantum materials and strong laser fields can result in non-equilibrium electronic states. Monolayer transition metal dichalcogenides, as direct-gap semiconductors with quantum confinement, offer opportunities for controlling excitons. However, characterizing strong-field driven exciton dynamics has been challenging.
Article
Nanoscience & Nanotechnology
Timo Paschen, Ryan Roussel, Lennart Seiffert, Bjoern Kruse, Christian Heide, Philip Dienstbier, Joshua Mann, James Rosenzweig, Thomas Fennel, Peter Hommelhoff
Summary: Enhanced near-fields at metallic nanostructures are utilized to generate ultrafast nanometric electron pulses and investigate fundamental ultrafast dynamics in electron emission. In this study, strong-field induced photoemission from a nanometer-sharp tungsten-covered silicon nanoblade is shown, and intensity-dependent electron energy spectra and yields are systematically measured. The research reveals the presence of elastic electron rescattering in the enhanced near-fields at the surface of the one-dimensional nanostructure, providing strong-field features from a one-dimensional object for the first time. The presented one-dimensional nanostructure enables the generation of high-energy electrons without target damage, making it of great interest for novel ultrafast photocathodes.
Article
Nanoscience & Nanotechnology
Huize Wang, Pablo Jimenez-Calvo, Marco Hepp, Mark Andrew Isaacs, Charles Otieno Ogolla, Ines Below-Lutz, Benjamin Butz, Volker Strauss
Summary: The use of laser carbonization can produce responsive carbon materials for the selective detection of volatile organic compounds. Adding nanoscale zinc oxide precursors significantly increases sensor response and measurable surface area. Surface polarity plays a significant role in the selectivity of the sensors.
ACS APPLIED NANO MATERIALS
(2023)
Article
Engineering, Electrical & Electronic
Johannes A. F. Lehmeyer, Timon Citak, Heiko B. Weber, Michael Krieger
Summary: The performance of 4H silicon carbide (SiC) MOSFETs relies on the quality of the SiC/silicon oxide interface, which often has a high density of interface traps. To address this issue, a fast and reliable characterization method is introduced using machine-learning techniques. This method extracts accurate performance parameters, including a quantitative estimate of the interface trap density, from the transfer characteristics of 4H-SiC MOSFETs. It has been successfully validated against Hall-effect measurements and applied to different types of MOSFETs.
ELECTRONICS LETTERS
(2023)
Article
Chemistry, Inorganic & Nuclear
Benjamin Kintzel, Michael Boehme, Daniel Plaul, Helmar Goerls, Nicolas Yeche, Felix Seewald, Hans -Henning Klauss, Andrei A. Zvyagin, Erik Kampert, Thomas Herrmannsdoerfer, Gwendolyne Pascua, Christopher Baines, Hubertus Luetkens, Winfried Plass
Summary: The trinuclear high-spin iron(III) complex [Fe3Cl3(saltag(Br))(py)(6)]ClO4 was synthesized and characterized. Magnetic measurements showed antiferromagnetic exchange between the iron(III) ions, resulting in a geometrically spin-frustrated ground state. High-field magnetization and muon-spin relaxation experiments confirmed the isotropic nature of the magnetic exchange and the absence of significant intermolecular interactions. The complex is considered an ideal candidate for studying spin-electric effects.
INORGANIC CHEMISTRY
(2023)
Article
Physics, Applied
E. Kodolitsch, A. Kabakow, V Sodan, M. Krieger, H. Weber, N. Tsavdaris
Summary: In this study, a triangular epitaxial defect is identified as a nucleation source for the growth of recombination-induced bar shaped stacking faults (BSSFs) in forward-biased 4H-SiC p-n diode test structures. Basal plane dislocations that converted into threading screw dislocations, located close to the surface of the epitaxial layer and included in the triangular defect, act as the nucleation source for the BSSFs. These BSSFs expand from the top towards the bottom of the epitaxial layer, which is a newly reported expansion mechanism.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2023)
Article
Chemistry, Multidisciplinary
Christian Dolle, Victor Oestreicher, Alberto M. Ruiz, Malte Kohring, Francisco Garnes-Portoles, Mingjian Wu, Gabriel Sanchez-Santolino, Alvaro Seijas-Da Silva, Marta Alcaraz, Yolita M. Eggeler, Erdmann Spiecker, Josep Canet-Ferrer, Antonio Leyva-Perez, Heiko B. Weber, Maria Varela, Jose J. Baldovi, Gonzalo Abellan
Summary: In this study, a few-layers bismuth hybrid material of electronic grade structural quality was synthesized using an unprecedented colloidal photocatalyzed, one-pot redox reaction. The material exhibited a sulfur-alkyl-functionalized reconstructed surface that prevented oxidation and resulted in a tuned electronic structure. The metallic behavior of the hybrid material was supported by ab initio predictions and room temperature transport measurements.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Chemistry, Multidisciplinary
Charles Otieno Ogolla, Yannik Loth, Tobias Haeger, Cedric Kreusel, Manuel Runkel, Thomas Riedl, Benjamin Butz, Anna Katharina Wigger, Stephan Schaeffer, Peter Haring Bolivar
Summary: In this study, THz-sSNOM was used for nanoscale imaging of CsPbBr3 thin films, and the local THz nanoscale conductivity was derived using a scattering model. The analysis of the obtained signals confirmed the presence of halide vacancies (VBr) and Pb-Pb bonds at the CsPbBr3 grain boundaries, which resulted in charge carrier trapping and nonradiative recombination. This study establishes THz-sSNOM as a powerful analysis platform for thin-film semiconductors like LHPs.
Article
Multidisciplinary Sciences
Jiaojian Shi, Haowei Xu, Christian Heide, Changan HuangFu, Chenyi Xia, Felipe de Quesada, Hongzhi Shen, Tianyi Zhang, Leo Yu, Amalya Johnson, Fang Liu, Enzheng Shi, Liying Jiao, Tony Heinz, Shambhu Ghimire, Ju Li, Jing Kong, Yunfan Guo, Aaron M. Lindenberg
Summary: The authors report giant room-temperature nonlinearity enhancements in Janus transition metal dichalcogenides, which may be leveraged through electronic band topology. The giant nonlinear optical response is linked to topological band mixing and strong inversion symmetry breaking due to the Janus structure. This work defines general protocols for designing materials with large nonlinearities and heralds the applications of topological materials in optoelectronics.
NATURE COMMUNICATIONS
(2023)
Article
Nanoscience & Nanotechnology
Christian Heide, Yuki Kobayashi, Amalya C. Johnson, Tony F. Heinz, David A. Reis, Fang Liu, Shambhu Ghimire
Summary: We report the layer-by-layer build-up of high-order harmonic generation (HHG) in artificially stacked transition metal dichalcogenides (TMDC) crystals. High-order harmonics up to the 19th order are generated by the interaction with a mid-infrared (MIR) driving laser. The generation of harmonics is sensitive to the number of layers and their relative orientation, with different stacking configurations showing different harmonic intensities.
Proceedings Paper
Computer Science, Hardware & Architecture
Lena Bergmann, Gregor Pobegen, Daniel Schlogl, Holger Schulze, Heiko B. Weber, Michael Krieger
Summary: A new, simplified and versatile current transient spectroscopy (CTS) measurement setup is demonstrated in this study. The depth profile of the PtH defect in fully processed silicon HV test diodes is investigated using this setup. It is found that a proton field stop (FS) at the backside of the test devices can effectively reduce the PtH defect concentration throughout the diode volume, and a strong correlation between the depth profile of the PtH defect and the leakage current is observed.
2022 IEEE 34TH INTERNATIONAL SYMPOSIUM ON POWER SEMICONDUCTOR DEVICES AND ICS (ISPSD)
(2022)
Article
Engineering, Electrical & Electronic
Marco Hepp, Huize Wang, Katharina Derr, Simon Delacroix, Sebastian Ronneberger, Felix F. Loeffler, Benjamin Butz, Volker Strauss
Summary: This study describes the mechanical properties of turbostratically graphitized carbon films obtained by carbon laser-patterning, and explores their potential application as bending or mechanical pressure sensors.
NPJ FLEXIBLE ELECTRONICS
(2022)