The Experts below are selected from a list of 7788 Experts worldwide ranked by ideXlab platform
David Goldhabergordon - One of the best experts on this subject based on the ideXlab platform.
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magnetic doping and kondo effect in bi 2 se 3 Nanoribbons
Nano Letters, 2010Co-Authors: Judy J Cha, Hailin Peng, David Goldhabergordon, J R Williams, Desheng Kong, Stefan Meister, Andrew Bestwick, Patrick Gallagher, Yi CuiAbstract:A simple surface band structure and a large bulk band gap have allowed Bi2Se3 to become a reference material for the newly discovered three-dimensional topological insulators, which exhibit topologically protected conducting surface states that reside inside the bulk band gap. Studying topological insulators such as Bi2Se3 in nanostructures is advantageous because of the high surface-to-volume ratio, which enhances effects from the surface states; recently reported Aharonov-Bohm oscillation in topological insulator Nanoribbons by some of us is a good example. Theoretically, introducing magnetic impurities in topological insulators is predicted to open a small gap in the surface states by breaking time-reversal symmetry. Here, we present synthesis of magnetically doped Bi2Se3 Nanoribbons by vapor-liquid-solid growth using magnetic metal thin films as catalysts. Although the doping concentration is less than approximately 2%, low-temperature transport measurements of the Fe-doped Bi2Se3 Nanoribbon devices show a clear Kondo effect at temperatures below 30 K, confirming the presence of magnetic impurities in the Bi2Se3 Nanoribbons. The capability to dope topological insulator nanostructures magnetically opens up exciting opportunities for spintronics.
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magnetic doping and kondo effect in bi2se3 Nanoribbons
arXiv: Materials Science, 2010Co-Authors: Judy J Cha, Hailin Peng, David Goldhabergordon, J R Williams, Desheng Kong, Stefan Meister, Andrew Bestwick, Patrick Gallagher, Yi CuiAbstract:A simple surface band structure and a large bulk band gap have allowed Bi2Se3 to become a reference material for the newly discovered three-dimensional topological insulators, which exhibit topologically-protected conducting surface states that reside inside the bulk band gap. Studying topological insulators such as Bi2Se3 in nanostructures is advantageous because of the high surface-to-volume ratio, which enhances effects from the surface states; recently reported Aharonov-Bohm oscillation in topological insulator Nanoribbons by some of us is a good example. Theoretically, introducing magnetic impurities in topological insulators is predicted to open a small gap in the surface states by breaking time-reversal symmetry. Here, we present synthesis of magnetically-doped Bi2Se3 Nanoribbons by vapor-liquid-solid growth using magnetic metal thin films as catalysts. Although the doping concentration is less than ~ 2%, low-temperature transport measurements of the Fe-doped Bi2Se3 Nanoribbon devices show a clear Kondo effect at temperatures below 30 K, confirming the presence of magnetic impurities in the Bi2Se3 Nanoribbons. The capability to dope topological insulator nanostructures magnetically opens up exciting opportunities for spintronics.
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quantum dot behavior in graphene nanoconstrictions
Nano Letters, 2009Co-Authors: Kathryn Todd, Hung Tao Chou, Sami Amasha, David GoldhabergordonAbstract:Graphene Nanoribbons display an imperfectly understood transport gap. We measure transport through Nanoribbon devices of several lengths. In long (≥250 nm) Nanoribbons we observe transport through multiple quantum dots in series, while shorter (≤60 nm) constrictions display behavior characteristic of single and double quantum dots. New measurements indicate that dot size may scale with constriction width. We propose a model where transport occurs through quantum dots that are nucleated by background disorder potential in the presence of a confinement gap.
Alex Zettl - One of the best experts on this subject based on the ideXlab platform.
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nanoimaging of low loss plasmonic waveguide modes in a graphene Nanoribbon
Nano Letters, 2021Co-Authors: Wenyu Zhao, Alex Zettl, Xiao Xiao, Yue Jiang, Kenji Watanabe, Takashi Taniguchi, Feng WangAbstract:Graphene Nanoribbons are predicted to support low-loss and tunable plasmonic waveguide modes with an ultrasmall mode area. Experimental observation of the plasmonic waveguide modes in graphene Nanoribbons, however, is challenging because conventional wet lithography has difficulty creating a clean graphene Nanoribbon with a low edge roughness. Here, we use a dry lithography method to fabricate ultraclean and low-roughness graphene Nanoribbons, which are then encapsulated in hexagonal boron nitride (hBN). We demonstrate low-loss plasmon propagation with a quality factor up to 35 in the ultraclean Nanoribbon waveguide using cryogenic infrared nanoscopy. In addition, we observe both the fundamental and the higher-order plasmonic waveguide modes for the first time. All the plasmon waveguide modes can be tuned through electrostatic gating. The observed tunable plasmon waveguide modes in ultraclean graphene Nanoribbons agree well with the finite-difference time-domain (FDTD) simulation results. They are promising for reconfigurable photonic circuits and devices at a subwavelength scale.
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Coronene-Based Graphene Nanoribbons Insulated by Boron Nitride Nanotubes: Electronic Properties of the Hybrid Structure
2018Co-Authors: Eduardo Gracia-espino, Hamid Reza Barzegar, Alex ZettlAbstract:We present a theoretical study on the formation of graphene Nanoribbonsvia polymerization of coronene moleculesinside the inner cavity of boron nitride nanotubes. We examine the electronic property of the hybrid system, and we show that the boron nitride nanotube does not significantly alter the electronic properties of the encapsulated graphene Nanoribbon. Motivated by previous experimental works, we examine graphene Nanoribbons with two different widths and investigate probable scenarios for defect formation and/or twisting of the resulting graphene Nanoribbons and their effect on the electronic properties of the hybrid system
Kathryn Todd - One of the best experts on this subject based on the ideXlab platform.
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Quantum dot behavior in graphene nanoconstrictions
Nano Letters, 2009Co-Authors: Kathryn Todd, Hung Tao Chou, Sami Amasha, Goldhaber Gordon DavidAbstract:Graphene Nanoribbons display an imperfectly understood transport gap. We measure transport through Nanoribbon devices of several lengths. In Nanoribbons of length greater than or equal to 250 nm we observe transport through multiple quantum dots in series, while shorter constrictions of length less than or equal to 60 nm display behavior characteristic of single and double quantum dots. Dot size scales with constriction width. We propose a model where transport occurs through quantum dots that are nucleated by background disorder potentials in the presence of a confinement gap.
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quantum dot behavior in graphene nanoconstrictions
Nano Letters, 2009Co-Authors: Kathryn Todd, Hung Tao Chou, Sami Amasha, David GoldhabergordonAbstract:Graphene Nanoribbons display an imperfectly understood transport gap. We measure transport through Nanoribbon devices of several lengths. In long (≥250 nm) Nanoribbons we observe transport through multiple quantum dots in series, while shorter (≤60 nm) constrictions display behavior characteristic of single and double quantum dots. New measurements indicate that dot size may scale with constriction width. We propose a model where transport occurs through quantum dots that are nucleated by background disorder potential in the presence of a confinement gap.
Yongwei Zhang - One of the best experts on this subject based on the ideXlab platform.
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polarity reversed robust carrier mobility in monolayer mos2 Nanoribbons
Journal of the American Chemical Society, 2014Co-Authors: Yongqing Cai, Gang Zhang, Yongwei ZhangAbstract:Using first-principles calculations and deformation potential theory, we investigate the intrinsic carrier mobility (μ) of monolayer MoS2 sheet and Nanoribbons. In contrast to the dramatic deterioration of μ in graphene upon forming Nanoribbons, the magnitude of μ in armchair MoS2 Nanoribbons is comparable to its sheet counterpart, albeit oscillating with ribbon width. Surprisingly, a room-temperature transport polarity reversal is observed with μ of hole (h) and electron (e) being 200.52 (h) and 72.16 (e) cm2 V–1 s–1 in sheet, and 49.72 (h) and 190.89 (e) cm2 V–1 s–1 in 4 nm Nanoribbon. The high and robust μ and its polarity reversal are attributable to the different characteristics of edge states inherent in MoS2 Nanoribbons. Our study suggests that width reduction together with edge engineering provide a promising route for improving the transport properties of MoS2 nanostructures.
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polarity reversed robust carrier mobility in monolayer mos2 Nanoribbons
arXiv: Materials Science, 2013Co-Authors: Yongqing Cai, Gang Zhang, Yongwei ZhangAbstract:Using first-principles calculations and deformation potential theory, we investigate the intrinsic carrier mobility ({\mu}) of monolayer MoS2 sheet and Nanoribbons. In contrast to the dramatic three orders of magnitude of deterioration of {\mu} in graphene upon forming Nanoribbons, the magnitude of {\mu} in armchair MoS2 Nanoribbons is comparable to that in monolayer MoS2 sheet, albeit oscillating with width. Surprisingly, a room-temperature transport polarity reversal is observed with {\mu} of hole (h) and electron (e) being 200.52 (h) and 72.16 (e) cm2V-1s-1 in sheet, and 49.72 (h) and 190.89 (e) cm2V-1s-1 in 4 nm-wide Nanoribbon. The robust magnitudes of {\mu} and polarity reversal are attributable to the different characteristics of edge states inherent in MoS2 Nanoribbons. Our study suggests that width-reduction together with edge engineering provide a promising route for improving the transport properties of MoS2 nanostructures.
Jie Chen - One of the best experts on this subject based on the ideXlab platform.
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chiral selective tunneling induced negative differential resistance in zigzag graphene Nanoribbon a theoretical study
Applied Physics Letters, 2008Co-Authors: Zhengfei Wang, Jinlong Yang, J G Hou, Q W Shi, Xiaoping Wang, Jie ChenAbstract:The electronic and phase-coherent transport properties of a doped zigzag graphene Nanoribbon are studied theoretically in this paper. The I-V curve of the device shows an interesting negative differential resistance (NDR) phenomenon. We found that the NDR is caused by the chiral tunneling of graphene, which is attributed to the symmetry of the eigenstates of individual subbands. This new physics finding is helpful for us to gain more insights about carrier transport in graphene Nanoribbons and to design graphene-based nanoelectronic devices.
