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Carbon nanotube reservoirs for self-healing materials
Lanzara, G,Yoon, Y,Liu, H,Peng, S,Lee, W-I IOP Pub 2009 Nanotechnology Vol.20 No.33
<P>A novel nanoreservoir made of carbon nanotubes (CNTs) is proposed for realizing tougher and automated self-healing materials. The advantages of the approach are that CNTs have the potential to play the role of reinforcing elements prior to and after sealing a crack and that the number of voids is reduced after the material and the CNTs themselves are healed. The focus of this paper is on investigating the feasibility of using CNTs as a nanoreservoir by analyzing the dynamics of a fluid flowing out of a ruptured single-walled CNT (SWNT), where the fluid resembles an organic healing agent. With this in mind the escaping mechanism of organic molecules stored inside a cracked SWNT was investigated through a molecular dynamics study. The study shows that, when a SWNT wall suffers the formation of a crack, a certain amount of organic molecules, stored inside the SWNT, escape into space in a few picoseconds. This phenomenon is found to depend on the temperature and on the size of the cracks. The results of this study indicate that CNTs have the potential to be successfully used to realize the next generation of stronger, lighter and self-healing materials. </P>
Emergence of Kondo Resonance in Graphene Intercalated with Cerium
Hwang, Jinwoong,Kim, Kyoo,Ryu, Hyejin,Kim, Jingul,Lee, Ji-Eun,Kim, Sooran,Kang, Minhee,Park, Byeong-Gyu,Lanzara, Alessandra,Chung, Jinwook,Mo, Sung-Kwan,Denlinger, Jonathan,Min, Byung Il,Hwang, Choong American Chemical Society 2018 NANO LETTERS Vol.18 No.6
<P>The interaction between a magnetic impurity, such as cerium (Ce) atom, and surrounding electrons has been one of the core problems in understanding many-body interaction in solid and its relation to magnetism. Kondo effect, the formation of a new resonant ground state with quenched magnetic moment, provides a general framework to describe many-body interaction in the presence of magnetic impurity. In this Letter, a combined study of angle-resolved photoemission (ARPES) and dynamic mean-field theory (DMFT) on Ce-intercalated graphene shows that Ce-induced localized states near Fermi energy, <I>E</I><SUB>F</SUB>, hybridized with the graphene π-band, exhibit gradual increase in spectral weight upon decreasing temperature. The observed temperature dependence follows the expectations from the Kondo picture in the weak coupling limit. Our results provide a novel insight how Kondo physics emerges in the sea of two-dimensional Dirac electrons.</P> [FIG OMISSION]</BR>
Temperature-Dependent Electron–Electron Interaction in Graphene on SrTiO<sub>3</sub>
Ryu, Hyejin,Hwang, Jinwoong,Wang, Debin,Disa, Ankit S.,Denlinger, Jonathan,Zhang, Yuegang,Mo, Sung-Kwan,Hwang, Choongyu,Lanzara, Alessandra American Chemical Society 2017 NANO LETTERS Vol.17 No.10
<P>The electron band structure of graphene on SrTiO3 substrate has been investigated as a function of temperature. The high-resolution angle-resolved photoemission study reveals that the spectral width at Fermi energy and the Fermi velocity of graphene on SrTiO3 are comparable to those of graphene on a BN substrate. Near the charge neutrality, the energy-momentum dispersion of graphene exhibits a strong deviation from the well-known linearity, which is magnified as temperature decreases. Such modification resembles the characteristics of enhanced electron electron interaction. Our results not only suggest that SrTiO3 can be a plausible candidate as a substrate material for applications in graphene-based electronics but also provide a possible route toward the realization of a new type of strongly correlated electron phases in the prototypical two-dimensional system via the manipulation of temperature and a proper choice of dielectric substrates.</P>
The electronic correlations in graphene standing on SrTiO₃ and platinum substrates
Jinwoong Hwang,Hyejin Ryu,Hwihyeon Hwang,Min-Jeong Kim,Ji-Eun Lee,Qin Zhou,Debin Wang,Ankit S. Disa,Jonathan Denlinger,Yuegang Zhang,Alessandra Lanzara,Sung-Kwan Mo,Choongyu Hwang 한국진공학회 2018 한국진공학회 학술발표회초록집 Vol.2018 No.2
Symmetry rules shaping spin-orbital textures in surface states
Gotlieb, Kenneth,Li, Zhenglu,Lin, Chiu-Yun,Jozwiak, Chris,Ryoo, Ji Hoon,Park, Cheol-Hwan,Hussain, Zahid,Louie, Steven G.,Lanzara, Alessandra American Physical Society 2017 Physical Review B Vol.95 No.24
<P>Strong spin-orbit coupling creates exotic electronic states such as Rashba and topological surface states, which hold promise for technologies involving the manipulation of spin. Only recently has the complexity of these surface states been appreciated: they are composed of several atomic orbitals with distinct spin textures in momentum space. A complete picture of the wave function must account for this orbital dependence of spin. We discover that symmetry constrains the way orbital and spin components of a state coevolve as a function of momentum, and from this, we determine the rules governing how the two degrees of freedom are interwoven. We directly observe this complexity in spin-resolved photoemission and ab initio calculations of the topological surface states of Sb(111), where the photoelectron spin direction near (Gamma) over bar is found to have a strong and unusual dependence on photon polarization. This dependence unexpectedly breaks down at large |k|, where the surface states mix with other nearby surface states. However, along mirror planes, symmetry protects the distinct spin orientations of different orbitals. Our discovery broadens the understanding of surface states with strong spin-orbit coupling, demonstrates the conditions that allow for optical manipulation of photoelectron spin, and will be highly instructive for future spintronics applications.</P>