Article
Multidisciplinary Sciences
Zengming Meng, Liangwei Wang, Wei Han, Fangde Liu, Kai Wen, Chao Gao, Pengjun Wang, Cheng Chin, Jing Zhang
Summary: The observation of strong correlations and superconductivity in twisted-bilayer graphene has generated significant interest in fundamental and applied physics. The moire pattern generated by the superposition of two twisted honeycomb lattices is crucial for the emergence of flat electronic bands and other unique properties. In this study, a quantum simulation of the superfluid to Mott insulator transition is demonstrated in twisted-bilayer square lattices using atomic Bose-Einstein condensates.
Article
Materials Science, Multidisciplinary
Zhiyu Dong, Andrey Chubukov, Leonid Levitov
Summary: We investigate the origin of superconductivity in Bernal bilayer graphene and propose an unconventional scenario of quantum-critical pairing driven by isospin fluctuations. The superconductivity, induced by a parallel magnetic field, persists above the Pauli limit, suggesting the presence of spin-triplet superconductivity. We demonstrate that an entirely repulsive interaction can lead to the emergence of superconductivity through a transformer mechanism involving frequency-dependent pairing effects.
Article
Chemistry, Multidisciplinary
Yasser Saleem, Katarzyna Sadecka, Marek Korkusinski, Daniel Miravet, Amintor Dusko, Pawel Hawrylak
Summary: We propose a theory on excitons in gated bilayer graphene quantum dots. By applying electrical gating to the bilayer graphene, an energy gap is opened, transforming it into a tunable semiconductor. Unlike in regular semiconductor quantum dots, metallic gates in our lateral structure confine both electrons and holes. Using an atomistic approach and exact diagonalization tools, we demonstrate the formation of strongly interacting and electrically tunable excitons. These excitons exhibit unique properties compared to those found in traditional semiconductor quantum dots, with their energy tunable across the terahertz to far infrared range. The conservation of spin, valley, and orbital angular momentum leads to a fine structure of excitons with a band of dark low-energy states, making this system a promising candidate for storage, detection, and emission of photons in the terahertz range.
Article
Chemistry, Multidisciplinary
Mingde Du, Luojun Du, Nan Wei, Wei Liu, Xueyin Bai, Zhipei Sun
Summary: The research team demonstrated an electrically tunable lateral junction at atomically sharp interfaces between mono- and bilayer graphene, systematically investigating the transport properties. They found that the difference in conductivity of graphene channels at the mono-bilayer interface depends greatly on the doping level, and the existence of a gate tunable junction provides a possible path for functional applications of graphene in next-generation electronics.
NANOSCALE ADVANCES
(2021)
Article
Materials Science, Multidisciplinary
Hasan M. Abdullah, Abderrahim El Mouhafid, Gokaran Shukla, Udo Schwingenschlogl
Summary: One of the key features of graphene is the chirality of the electrons. Introduction of an external perturbation can change the chirality and significantly modify the quantum transport. This study explores the tunneling in AB-stacked bilayer graphene in the presence of an in-plane pseudomagnetic field and an out-of-plane electric field.
Article
Multidisciplinary Sciences
Anna M. Seiler, Fabian R. Geisenhof, Felix Winterer, Kenji Watanabe, Takashi Taniguchi, Tianyi Xu, Fan Zhang, R. Thomas Weitz
Summary: This study reports the observation of a cascade of correlated phases in Bernal bilayer graphene, including Stoner ferromagnets and a topologically non-trivial crystal, providing new possibilities for studying strongly correlated electrons in a simple system.
Article
Materials Science, Multidisciplinary
N. Girotto, L. Linhart, F. Libisch
Summary: Stacking two layers of slightly twisted two-dimensional materials alters the physical properties of the resulting bilayer, including electronic and phononic band structures. Our findings suggest that manipulating phononic and electronic properties through suitable twisting structures provides an opportunity to investigate the contributions of electron-phonon interactions to the observed correlated states.
Article
Nanoscience & Nanotechnology
Wen-Wu Xie, Yong-Mei Zhang, Zhi Ping Niu
Summary: The presence of interlayer potential, Rashba spin-orbit coupling, and exchange field leads to a topological phase transition in bilayer graphene. The sharp peaks of longitudinal conductivity at low frequency contribute more to energy radiation. Energy and angular momentum radiation can be used to distinguish different topological phases.
PHYSICA E-LOW-DIMENSIONAL SYSTEMS & NANOSTRUCTURES
(2023)
Article
Materials Science, Multidisciplinary
Danhong Wu, Yiping Lin, Lingxiao Xiong, Junjie Li, Tiantian Luo, Deyi Chen, Feipeng Zheng
Summary: Intercalating rubidium boosts weak superconductivity in bilayer PtTe2 to T-c = 8 K with high density of states at Fermi energy and mass-enhancement parameter, while potassium intercalation shows comparable effects to rubidium intercalation, suggesting these superconductors provide promising platforms for studying novel quantum physics associated with two-dimensional superconductivity.
Article
Physics, Multidisciplinary
Glenn Wagner, Yves H. Kwan, Nick Bultinck, Steven H. Simon, S. A. Parameswaran
Summary: We investigate the phase diagram of twisted bilayer graphene (TBG) in the normal state, considering doping and strain dependence. Our comprehensive calculations reveal the competition and coexistence of three intertwined orders: a fully symmetric phase, flavor-symmetry-breaking states, and an incommensurate Kekule spiral (IKS) order. The IKS order is found to be ubiquitous for noninteger doping as well, consistent with experimental observations of electronic compressibility and Fermi surface structure. This study suggests a unified picture of the phase diagram in terms of IKS order.
PHYSICAL REVIEW LETTERS
(2022)
Article
Chemistry, Multidisciplinary
Aditya Jayaraman, Kimberly Hsieh, Bhaskar Ghawri, Phanibhusan S. Mahapatra, Kenji Watanabe, Takashi Taniguchi, Arindam Ghosh
Summary: Resolving low-energy features in the density of states (DOS) is crucial for understanding rich novel phenomena in graphene-based 2D heterostructures. Through investigating thermoelectric power, effective probing of fine changes in the DOS of bilayer graphene (BLG) was demonstrated, revealing additional entropy features near the charge neutrality point (CNP) in gapped BLG. This apparent violation of the Mott formula can be quantitatively explained by considering the effects of trigonal warping, possibly serving as evidence for a Lifshitz transition.
Article
Physics, Multidisciplinary
D. A. Bandurin, A. Principi, I. Y. Phinney, T. Taniguchi, K. Watanabe, P. Jarillo-Herrero
Summary: This study demonstrates that small-angle twisted bilayer graphene provides a highly tunable system for exploring interactions-limited electron conduction. Through the development of e-h drag theory, we reveal strong mutual friction between electrons and holes and clarify the conduction mechanisms in charge-neutral SATBG.
PHYSICAL REVIEW LETTERS
(2022)
Article
Materials Science, Multidisciplinary
V. Apinyan, T. K. Kopec
Summary: This paper investigates the antiferromagnetic and excitonic correlations in AA-stacked bilayer graphene, considering the impact of an external electric field potential and different particle-filling regimes. The study reveals that antiferromagnetism and excitonic phases can coexist away from half-filling, with the presence of a critical Coulomb interaction potential determining the transition between single-valued and triple-valued excitonic states.
Article
Materials Science, Multidisciplinary
V. Nam Do
Summary: Research has shown that Dirac points emerge in sliding bilayer graphene due to band crossings in the electronic structure. The compatibility relations between symmetries of eigenstates at high-symmetry k points in the Brillouin zone guarantee band crossings of energy dispersion curves at generic k points. The presence of Dirac points governs the geometrical and topological properties of the Fermi energy surfaces, leading to Lifshitz transition and transport properties of the systems.
Article
Materials Science, Multidisciplinary
Panch Ram, Detlef Beckmann, Romain Danneau, Wolfgang Belzig
Summary: In this study, we investigate the changes in Andreev and normal reflection processes by applying a displacement field in a bilayer graphene-superconductor junction. The reflection probabilities were calculated under different conditions, and it was found that the reflection mode can be adjusted by tuning the Fermi energy. The transition from retro to specular reflection is amplified when the displacement field is relatively small. Furthermore, we discovered the simultaneous existence of double Andreev reflections and double normal reflections when the displacement field is comparable to the interlayer coupling strength.
Article
Physics, Applied
Gautam Gaddemane, William G. Vandenberghe, Maarten L. Van de Put, Edward Chen, Massimo Fischettit
JOURNAL OF APPLIED PHYSICS
(2018)
Article
Engineering, Electrical & Electronic
Jingtian Fang, Mahmud Reaz, Stephanie L. Weeden-Wright, Ronald D. Schrimpf, Robert A. Reed, Robert A. Weller, Massimo V. Fischetti, Sokrates T. Pantelides
IEEE TRANSACTIONS ON NUCLEAR SCIENCE
(2019)
Article
Materials Science, Multidisciplinary
Kristof Moors, Antonino Contino, Maarten L. Van de Put, William G. Vandenberghe, Massimo Fischetti, Wim Magnus, Bart Soree
PHYSICAL REVIEW MATERIALS
(2019)
Article
Physics, Applied
M. V. Fischetti, P. D. Yoder, M. M. Khatami, G. Gaddemane, M. L. Van de Put
APPLIED PHYSICS LETTERS
(2019)
Article
Chemistry, Physical
Sanjay Gopalan, Gautam Gaddemane, Maarten L. Van de Put, Massimo V. Fischetti
Article
Physics, Applied
Pratik B. Vyas, Maarten L. Van de Put, Massimo V. Fischetti
PHYSICAL REVIEW APPLIED
(2020)
Article
Engineering, Electrical & Electronic
Gautam Gaddemane, Sanjay Gopalan, Maarten L. Van de Put, Massimo V. Fischetti
Summary: Ab initio methods have become popular in evaluating intrinsic carrier transport properties in 2D semiconductors, but a large discrepancy exists in literature due to physical approximations and different 'flavors' of DFT used. The limitations of current ab initio methods in calculating carrier transport properties still need further research.
JOURNAL OF COMPUTATIONAL ELECTRONICS
(2021)
Article
Engineering, Electrical & Electronic
Gautam Gaddemane, Maarten L. Van de Put, William G. Vandenberghe, Edward Chen, Massimo V. Fischetti
Summary: Experimental studies on 2D materials are still in the early stages, with theoretical research mostly focusing on room-temperature carrier mobility. As devices shrink to nanometer scales, room-temperature carrier mobility may not be the main factor controlling the performance of devices based on 2D materials, due to electronic transport occurring under strong off-equilibrium conditions. Our simulations using Monte Carlo method with the Poisson equation reveal significant intrinsic limitations to the performance of phosphorene as a channel material in nanotransistors.
JOURNAL OF COMPUTATIONAL ELECTRONICS
(2021)
Article
Physics, Applied
Sokrates T. Pantelides, D. Greg Walker, Mahmud Reaz, Massimo V. Fischetti, Ronald D. Schrimpf
Summary: This study reexamines the foundations of Shockley's equation and provides a robust theoretical justification for its kinetic-energy component and phonon component. The research findings show that Shockley's equation's exceptional applicability remains unchanged with a single-parameter fit.
APPLIED PHYSICS LETTERS
(2022)
Article
Engineering, Electrical & Electronic
Emeric Deylgat, Edward Chen, Massimo Fischetti, Bart Soree, William G. Vandenberghe
Summary: This study compares the contact resistance and image-force barrier lowering (IFBL) for four different metal-dielectric-two-dimensional (2D) material configurations. The analysis considers different geometries of edge contacts and calculates the contact resistivity using the WKB approximation. The optimal configuration achieves a 50-fold reduction in contact resistance compared to the situation without considering IFBL.
SOLID-STATE ELECTRONICS
(2022)
Article
Physics, Applied
Sanjay Gopalan, Maarten L. Van de Put, Gautam Gaddemane, Massimo Fischetti
Summary: This paper discusses the effect of the dielectric environment on electronic transport in two-dimensional transition metal dichalcogenides monolayers. The study finds that insulators with a high dielectric constant can significantly improve carrier mobility, but scattering with interface hybrid excitations negates this gain. Additionally, deviations from the expected trend are observed when using polar materials as gate insulators, as well as the effect of screening by metal gates.
PHYSICAL REVIEW APPLIED
(2022)
Article
Nanoscience & Nanotechnology
Madhuchhanda Brahma, Maarten L. L. Van de Put, Edward Chen, Massimo V. V. Fischetti, William G. G. Vandenberghe
Summary: In this study, the impact of surrounding dielectrics and image-force barrier-lowering on the resistance of Schottky edge-contacts in metal-2D-material transistors is investigated. The electrostatic potential is calculated numerically using the Poisson equation, while the transmission probability is computed using the Wentzel-Kramers-Brillouin approximation. The results show that low-kappa surrounding dielectrics are crucial for achieving low resistance monolayer-TMD edge-contacts.
NPJ 2D MATERIALS AND APPLICATIONS
(2023)
Article
Chemistry, Physical
Yeonghun Lee, Xiaolong Yao, Massimo Fischetti, Kyeongjae Cho
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2020)
Proceedings Paper
Engineering, Electrical & Electronic
Akash A. Laturia, Maarten L. Van de Put, Massimo V. Fischetti, William G. Vandenberghe
2018 76TH DEVICE RESEARCH CONFERENCE (DRC)
(2018)
Article
Materials Science, Multidisciplinary
Massimo V. Fischetti, Arup Polley