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Giant and Tunable Bosonic Quantum Interference Induced by Two-Dimensional Metals
Authors:
Kunyan Zhang,
Rinu Abraham Maniyara,
Yuanxi Wang,
Arpit Jain,
Maxwell T. Wetherington,
Thuc T. Mai,
Chengye Dong,
Timothy Bowen,
Ke Wang,
Slava V. Rotkin,
Angela R. Hight Walker,
Vincent H. Crespi,
Joshua Robinson,
Shengxi Huang
Abstract:
Harnessing quantum interference among bosons provides significant opportunities as bosons often carry longer coherence time than fermions. As an example of quantum interference, Fano resonance involving phonons or photons describes the coupling between discrete and continuous states, signified by an asymmetric spectral lineshape. Utilizing photon-based Fano resonance, molecule sensing with ultra-h…
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Harnessing quantum interference among bosons provides significant opportunities as bosons often carry longer coherence time than fermions. As an example of quantum interference, Fano resonance involving phonons or photons describes the coupling between discrete and continuous states, signified by an asymmetric spectral lineshape. Utilizing photon-based Fano resonance, molecule sensing with ultra-high sensitivity and ultrafast optical switching has been realized. However, phonon-based Fano resonance, which would expand the application space to a vaster regime, has been less exploited because of the weak coupling between discrete phonons with continuous states such as electronic continuum. In this work, we report the discovery of giant phonon-based Fano resonance in a graphene/2D Ag/SiC heterostructure. The Fano asymmetry, being proportional to the coupling strength, exceeds prior reports by two orders of magnitude. This Fano asymmetry arises from simultaneous frequency and lifetime matching between discrete and continuous phonons of SiC. The introduction of 2D Ag layers restructures SiC at the interface and facilitates resonant scattering to further enhance the Fano asymmetry, which is not achievable with conventional Ag thin films. With these unique properties, we demonstrated that the phonon-based Fano resonance can be used for ultrasensitive molecule detection at the single-molecule level. Our work highlights strong Fano resonance in the phononic system, opening avenues for engineering quantum interference based on bosons. Further, our findings provide opportunities for advancing phonon-related applications, including biochemical sensing, quantum transduction, and superconductor-based quantum computing.
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Submitted 30 September, 2024;
originally announced October 2024.
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Large-Area Intercalated 2D-Pb/Graphene Heterostructure as a Platform for Generating Spin-Orbit Torque
Authors:
Alexander Vera,
Boyang Zheng,
Wilson Yanez,
Kaijie Yang,
Seong Yeoul Kim,
Xinglu Wang,
Jimmy C. Kotsakidis,
Hesham El-Sherif,
Gopi Krishnan,
Roland J. Koch,
T. Andrew Bowen,
Chengye Dong,
Yuanxi Wang,
Maxwell Wetherington,
Eli Rotenberg,
Nabil Bassim,
Adam L. Friedman,
Robert M. Wallace,
Chaoxing Liu,
Nitin Samarth,
Vincent H. Crespi,
Joshua A. Robinson
Abstract:
A scalable platform to synthesize ultrathin heavy metals may enable high efficiency charge-to-spin conversion for next-generation spintronics. Here we report the synthesis of air-stable, epitaxially registered monolayer Pb underneath bilayer graphene on SiC (0001) by confinement heteroepitaxy (CHet). Diffraction, spectroscopy, and microscopy reveal CHet-based Pb intercalation predominantly exhibit…
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A scalable platform to synthesize ultrathin heavy metals may enable high efficiency charge-to-spin conversion for next-generation spintronics. Here we report the synthesis of air-stable, epitaxially registered monolayer Pb underneath bilayer graphene on SiC (0001) by confinement heteroepitaxy (CHet). Diffraction, spectroscopy, and microscopy reveal CHet-based Pb intercalation predominantly exhibits a mottled hexagonal superstructure due to an ordered network of Frenkel-Kontorova-like domain walls. The system's air stability enables ex-situ spin torque ferromagnetic resonance (ST-FMR) measurements that demonstrate charge-to-spin conversion in graphene/Pb/ferromagnet heterostructures with a 1.5x increase in the effective field ratio compared to control samples.
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Submitted 20 August, 2024; v1 submitted 13 May, 2022;
originally announced May 2022.
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Proximity-Induced Superconductivity in Epitaxial Topological Insulator/Graphene/Gallium Heterostructures
Authors:
Cequn Li,
Yi-Fan Zhao,
Alexander Vera,
Omri Lesser,
Hemian Yi,
Shalini Kumari,
Zijie Yan,
Chengye Dong,
Timothy Bowen,
Ke Wang,
Haiying Wang,
Jessica L. Thompson,
Kenji Watanabe,
Takashi Taniguchi,
Danielle Reifsnyder Hickey,
Yuval Oreg,
Joshua A. Robinson,
Cui-Zu Chang,
Jun Zhu
Abstract:
The introduction of superconductivity to the Dirac surface states of a topological insulator leads to a topological superconductor, which may support topological quantum computing through Majorana zero modes. The development of a scalable material platform is key to the realization of topological quantum computing. Here we report on the growth and properties of high-quality (Bi,Sb)2Te3/graphene/ga…
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The introduction of superconductivity to the Dirac surface states of a topological insulator leads to a topological superconductor, which may support topological quantum computing through Majorana zero modes. The development of a scalable material platform is key to the realization of topological quantum computing. Here we report on the growth and properties of high-quality (Bi,Sb)2Te3/graphene/gallium heterostructures. Our synthetic approach enables atomically sharp layers at both hetero-interfaces, which in turn promotes proximity-induced superconductivity that originates in the gallium film. A lithography-free, van der Waals tunnel junction is developed to perform transport tunneling spectroscopy. We find a robust, proximity-induced superconducting gap formed in the Dirac surface states in 5-10 quintuple-layer (Bi,Sb)2Te3/graphene/gallium heterostructures. The presence of a single Abrikosov vortex, where the Majorana zero modes are expected to reside, manifests in discrete conductance changes. The present material platform opens up opportunities for understanding and harnessing the application potential of topological superconductivity.
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Submitted 13 February, 2023; v1 submitted 5 May, 2022;
originally announced May 2022.
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Unexpected Near-Infrared to Visible Non-linear Optical Properties from Two-Dimensional Polar Metals
Authors:
Megan A. Steves,
Yuanxi Wang,
Natalie Briggs,
Tian Zhao,
Hesham El-Sherif,
Brian Bersch,
Shruti Subramanian,
Chengye Dong,
Timothy Bowen,
Ana De La Fuente Duran,
Katharina Nisi,
Margaux Lassaunière,
Ursula Wurstbauer,
Nabil Bassim,
Jose J. Fonseca,
Jeremy T. Robinson,
Vincent Crespi,
Joshua Robinson,
Kenneth L. Knappenberger Jr
Abstract:
Near-infrared-to-visible second harmonic generation from air-stable two-dimensional polar gallium and indium metals is described. The photonic properties of 2D metals - including the largest second-order susceptibilities reported for metals (approaching 10nm$^2$/V) - are determined by the atomic-level structure and bonding of two-to-three-atom-thick crystalline films. The bond character evolved fr…
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Near-infrared-to-visible second harmonic generation from air-stable two-dimensional polar gallium and indium metals is described. The photonic properties of 2D metals - including the largest second-order susceptibilities reported for metals (approaching 10nm$^2$/V) - are determined by the atomic-level structure and bonding of two-to-three-atom-thick crystalline films. The bond character evolved from covalent to metallic over a few atomic layers, changing the out-of-plane metal-metal bond distances by approximately ten percent (0.2 $\unicode{x212B}$), resulting in symmetry breaking and an axial electrostatic dipole that mediated the large nonlinear response. Two different orientations of the crystalline metal atoms, corresponding to lateral displacements < 2 $\unicode{x212B}$, persisted in separate micron-scale terraces to generate distinct harmonic polarizations. This strong atomic-level structure-property interplay suggests metal photonic properties can be controlled with atomic precision.
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Submitted 24 August, 2020; v1 submitted 3 April, 2020;
originally announced April 2020.
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Epitaxial Graphene Intercalation: A Route to Graphene Modulation and Unique 2D Materials
Authors:
Natalie Briggs,
Zewdu M. Gebeyehu,
Alexander Vera,
Tian Zhao,
Ke Wang,
Ana De La Fuente Duran,
Brian Bersch,
Timothy Bowen,
Kenneth L. Knappenberger, Jr.,
Joshua A. Robinson
Abstract:
Intercalation of atomic species through epitaxial graphene layers began only a few years following its initial report in 2004. The impact of intercalation on the electronic properties of the graphene is well known; however, the intercalant itself can also exhibit intriguing properties not found in nature. This suggests that a shift in the focus of epitaxial graphene intercalation studies may lead…
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Intercalation of atomic species through epitaxial graphene layers began only a few years following its initial report in 2004. The impact of intercalation on the electronic properties of the graphene is well known; however, the intercalant itself can also exhibit intriguing properties not found in nature. This suggests that a shift in the focus of epitaxial graphene intercalation studies may lead to fruitful exploration of many new forms of traditionally 3D materials. In the following forward-looking review, we summarize the primary techniques used to achieve and characterize EG intercalation, and introduce a new, facile approach to readily achieve metal intercalation at the graphene/silicon carbide interface. We show that simple thermal evaporation-based methods can effectively replace complicated synthesis techniques to realize large-scale intercalation of non-refractory metals. We also show that these methods can be extended to the formation of compound materials based on intercalation. Two-dimensional (2D) silver (2D-Ag) and large-scale 2D gallium nitride (2D-GaNx) are used to demonstrate these approaches.
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Submitted 30 May, 2019; v1 submitted 22 May, 2019;
originally announced May 2019.