Article
Chemistry, Multidisciplinary
Anna Kuzmina, Markus Parzefall, Patrick Back, Takashi Taniguchi, Kenji Watanabe, Achint Jain, Lukas Novotny
Summary: By controlled stacking of graphene layers, the limitation of single-layer graphene as a material for light-emitting devices has been overcome, enabling twist-controlled resonant light emission. Experimental findings show light emission irrespective of the crystallographic alignment between the graphene electrodes, with a spectrally tunable resonant peak in the near-infrared range.
Article
Engineering, Electrical & Electronic
Congya You, Wenjie Deng, Xiaoqing Chen, Wencai Zhou, Zilong Zheng, Boxing An, Songyu Li, Bo Wang, Yongzhe Zhang
Summary: This study presents a vertically stacked tunneling photodetector based on WSe2/graphene/WS2 van der Waals heterostructure. By introducing graphene film into the WSe2/WS2 interface, the interface composition was improved and Fowler-Nordheim tunneling was enhanced. The device shows high responsivity, detectivity, and photocurrent/dark current ratio, outperforming devices without graphene.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2021)
Article
Chemistry, Multidisciplinary
Damon James Carrad, Lukas Stampfer, Dags Olsteins, Christian Emmanuel Noes Petersen, Sabbir A. Khan, Peter Krogstrup, Thomas Sand Jespersen
Summary: Semiconductor/superconductor hybrids have been studied to explore novel physics and develop new technologies. In this study, Josephson junctions defined by shadow epitaxy on InAsSb/Al nanowires were investigated. The devices exhibited gate-tunable supercurrents at low temperatures and multiple Andreev reflections at finite voltage bias. Under microwave irradiation, characteristic oscillating sidebands at quantized energies were observed, which confirmed a recently suggested modification of a classical equation. The measurements provided evidence for the effective charge transferred by the tunneling process and suggested photon-assisted tunneling as a powerful method for identifying low-energy spectral features in hybrid Josephson devices.
Article
Chemistry, Multidisciplinary
Zongqi Bai, Yang Xiao, Qing Luo, Miaomiao Li, Gang Peng, Zhihong Zhu, Fang Luo, Mengjian Zhu, Shiqiao Qin, Kostya Novoselov
Summary: The emergence of two-dimensional materials has led to important applications in electronic and optoelectronic devices. However, there are limitations such as low ON/OFF ratio and Schottky barrier formation. In this study, highly tunable field-effect tunneling transistors based on vertical graphene-WS2-graphene heterostructures were demonstrated, overcoming these limitations and achieving low off-state current, high ON/OFF ratio, and controllable carrier transport polarity.
Article
Multidisciplinary Sciences
Alexander Kerelsky, Carmen Rubio-Verdu, Lede Xian, Dante M. Kennes, Dorri Halbertal, Nathan Finney, Larry Song, Simon Turkel, Lei Wang, Kenji Watanabe, Takashi Taniguchi, James Hone, Cory Dean, Dmitri N. Basov, Angel Rubio, Abhay N. Pasupathy
Summary: This study demonstrates the formation of emergent correlated phases in multilayer rhombohedral graphene without the need for twisted van der Waals layers. The study shows that two layers of bilayer graphene twisted by a tiny angle can host large regions of uniform rhombohedral four-layer graphene with a sharp van Hove singularity. Furthermore, the study suggests that the broken symmetry state in ABCA graphene could be attributed to a charge-transfer excitonic insulator or a ferrimagnet.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2021)
Article
Multidisciplinary Sciences
Sein Park, Wonjun Lee, Seong Jang, Yong-Bin Choi, Jinho Park, Woochan Jung, Kenji Watanabe, Takashi Taniguchi, Gil Young Cho, Gil-Ho Lee
Summary: Engineering quantum states through light-matter interaction has created a new paradigm in condensed-matter physics. In this study, steady Floquet-Andreev states were successfully generated in graphene Josephson junctions and their spectral characteristics were quantitatively analyzed. This research provides a foundation for understanding and engineering non-equilibrium quantum states in nanodevices.
Article
Physics, Applied
V. A. Sevriuk, W. Liu, J. Ronkko, H. Hsu, F. Marxer, T. F. Morstedt, M. Partanen, J. Rabina, M. Venkatesh, J. Hotari, L. Gronberg, J. Heinsoo, T. Li, J. Tuorila, K. W. Chan, J. Hassel, K. Y. Tan, M. Mottonen
Summary: In this research, the authors present their recent results on a qubit reset scheme based on a quantum-circuit refrigerator. They use photon-assisted quasiparticle tunneling to decrease the energy relaxation time of the qubit during operation. The experiment involves a transmon qubit with dispersive readout, and the reset is achieved through capacitively coupling the qubit to the quantum-circuit refrigerator.
APPLIED PHYSICS LETTERS
(2022)
Article
Materials Science, Multidisciplinary
David Koprivica, Eran Sela
Summary: We studied tunnel junctions with a two-dimensional ferroelectric material sandwiched between graphene electrodes. By formulating a theory for the interplay of polarization and induced free charges, considering quantum capacitance effects, we predicted a gate-sensitive voltage difference between polar domains. This voltage difference can be measured using electrostatic force microscopy. Incorporating this theory into tunneling current-voltage characteristics, we identified a resonance peak associated with aligned Dirac cones as a highly sensitive probe of the polarization. This opens up possibilities for device applications with thin polar layers for ultra-high-density memory.
Article
Chemistry, Multidisciplinary
Yi-Ying Sung, Harmina Vejayan, Christopher J. Baddeley, Neville V. Richardson, Federico Grillo, Renald Schaub
Summary: On-surface synthesis with designer precursor molecules is an effective method for preparing graphene nanoribbons (GNRs) with tunable electronic properties. The band gap of GNRs doped with heteroatoms remains unchanged, but hydrogenation can engineer a tunable band gap. Surface-confined hydrogenation studies on 7-armchair GNRs grown on Au(111) surfaces reveal a self-limited hydrogenation process. The electronic properties of the GNR/Au(111) system can be modified by edge and basal-plane hydrogenation, and a mechanism for the hydrogenation process is proposed.
Article
Chemistry, Physical
Nadire Nayir, Mert Y. Sengul, Anna L. Costine, Petra Reinke, Siavash Rajabpour, Anushka Bansal, Azimkhan Kozhakhmetov, Joshua Robinson, Joan M. Redwing, Adri van Duin
Summary: This study investigates the defect-mediated surface interactions of gallium metals and trimethyl-gallium molecules with graphene using a combination of theory and experiments. The results reveal the presence of defects in graphene, which act as pathways for gallium intercalation. The study shows that the adsorption of gallium and trimethyl-gallium on graphene is strongly influenced by the presence and size of defects, and these defects catalyze surface reactions.
Article
Materials Science, Multidisciplinary
Ding-Fu Shao, Shu-Hui Zhang, Rui-Chun Xiao, Zi-An Wang, W. J. Lu, Y. P. Sun, Evgeny Y. Tsymbal
Summary: In this study, we demonstrate the realization of a spin-neutral tunneling anomalous Hall effect (TAHE) in an antiferromagnetic (AFM) tunnel junction driven by spin-neutral currents. We show that the symmetry mismatch between the AFM electrode and the nonmagnetic barrier with strong spin-orbit coupling (SOC) results in spin-dependent momentum filtering, generating transverse Hall currents in each electrode. This finding opens up new possibilities for research in magnetoelectronics and spintronics.
Article
Chemistry, Multidisciplinary
Luke W. Smith, Jack O. Batey, Jack A. Alexander-Webber, Yu-Chiang Hsieh, Shin- Fung, Tom Albrow-Owen, Harvey E. Beere, Oliver J. Burton, Stephan Hofmann, David A. Ritchie, Michael Kelly, Tse-Ming Chen, Hannah J. Joyce, Charles G. Smith
Summary: This study investigates the insulating states in monolayer graphene grown by chemical vapor deposition (CVD) and wet transferred on Al2O3 without specialized fabrication techniques. The results show the existence of insulating properties and the opening of an energy gap induced by the magnetic field in a graphene device with a bottleneck. A locally high-quality region within the bottleneck dominates transport and causes the device to behave as an insulating tunnel junction. The use of wet transfer fabrication techniques and multiplexing demonstrates the convenience of these scalable and reasonably simple methods for finding high-quality devices for fundamental physics research and functional properties.
Article
Physics, Applied
Yuta Seo, Satoru Masubuchi, Momoko Onodera, Yijin Zhang, Rai Moriya, Kenji Watanabe, Takashi Taniguchi, Tomoki Machida
Summary: We demonstrate twist-controlled resonant tunneling in a monolayer graphene/hexagonal boron nitride/ABA-stacked trilayer graphene van der Waals junction. By aligning the graphene flakes with a small twist angle, resonant tunneling attributed to the conservation of momentum and energy between the two layers was observed, providing a method to determine band parameters and probe the band dispersion of different materials.
APPLIED PHYSICS LETTERS
(2022)
Article
Chemistry, Multidisciplinary
Alina Kononov, Andre Schleife
Summary: Using first-principles calculations, the study uncovers and explains a new type of anomalous low-velocity stopping effect in proton-irradiated graphene, attributing it to enhanced electron capture from sigma- and pi-orbitals. The analysis of electron emission suggests that backward emission is more sensitive to proton trajectory, potentially leading to higher contrast images in ion microscopy. For slow protons, a steep drop in emission is observed, consistent with predictions from analytical models.
Article
Physics, Multidisciplinary
Han-Zhao Tang, Xiao-Tong Liao, Zhi-Bin Zhang, Yan-Xia Liu, Zhuo Gu
Summary: The study uses nonequilibrium Green's function method to investigate transport properties through a regular B-form single-stranded DNA with Majorana zero modes in the presence of a microwave field. It is found that the photon-coupled Majorana zero mode acts as a series of channels, generating photon peaks in tunneling spectroscopy. Photon-assisted processes with Majorana zero mode can be regulated by gate voltage, providing a potential method for detecting non-zero energy Majorana zero modes in organic molecules.
