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The time-window for processing electron spin information (spintronics) in solid-state quantum electronic devices is determined by the spin-lattice (T1) and spin-spin (T2) relaxation times of electrons. Minimising the effects of spin-orbit…

Materials Science · Physics 2016-11-24 Bálint Náfrádi , Mohammad Choucair , Klaus-Peter Dinse , László Forró

We present a x-ray dichroism study of graphite surfaces that addresses the origin and magnitude of ferromagnetism in metal-free carbon. We find that, in addition to carbon $\pi$ states, also hydrogen-mediated electronic states exhibit a net…

Materials Science · Physics 2015-05-13 H. Ohldag , P. Esquinazi , E. Arenholz , D. Spemann , M. Rothermel , A. Setzer , T. Butz

Predictions state that graphene can spontaneously develop magnetism from the Coulomb repulsion of its $\pi$-electrons, but its experimental verification has been a challenge. Here, we report on the observation and manipulation of individual…

Mesoscale and Nanoscale Physics · Physics 2019-01-15 Jingcheng Li , Sofia Sanz , Martina Corso , Deung Jang Choi , Diego Peña , Thomas Frederiksen , Jose Ignacio Pascual

Graphene is a nonmagnetic semimetal and cannot be directly used as electronic or spintronic devices. We demonstrate that graphene quantum dots (GQDs) can exhibit strong edge magnetism and tunable energy gaps due to the presence of localized…

Materials Science · Physics 2017-11-01 Wei Hu , Yi Huang , Lin Lin , Erjun Kan , Xingxing Li , Chao Yang , Jinlong Yang

Void defect is a possible origin of ferromagnetic like feature of pure carbon material. Applying density functional theory to void defect induced graphene nano ribbon (GNR), a detailed relationship between multiple spin state and structure…

Materials Science · Physics 2021-07-06 Norio Ota , Laszlo Nemes

The edge reconstruction of zigzag graphene nanoribbons to a stable line of alternatively fused seven and five membered rings with hydrogen passivation has been studied within density functional theory with both localized and extended basis…

Materials Science · Physics 2009-11-17 Sudipta Dutta , Swapan K. Pati

We investigate the edge-state magnetism of graphene nanoribbons using projective quantum Monte Carlo simulations and a self-consistent mean-field approximation of the Hubbard model. The static magnetic correlations are found to be short…

Mesoscale and Nanoscale Physics · Physics 2011-06-13 Hélène Feldner , Zi Yang Meng , Thomas C. Lang , Fakher F. Assaad , Stefan Wessel , Andreas Honecker

We have studied the magnetotransport of conical and disk-shaped nanocarbon particles in magnetic fields $\left|B\right|\leq9\:\mathrm{T}$ at temperatures $2\leq T\leq300\:\mathrm{K}$ to characterize electron scattering in a three…

Mesoscale and Nanoscale Physics · Physics 2014-07-28 Jozef Černák , Geir Helgesen , Fredrik Sydow Hage , Jozef Kováč

Armchair graphene nanoribbons with different proportions of edge oxygen atoms are investigated by using crystal orbital method based on density functional theory. All the nanoribbons are energetically favorable, although buckled edges are…

Materials Science · Physics 2014-11-07 Hongyu Ge , Guo Wang , Yi Liao

We report production of nanostructured carbon foam by a high-repetition-rate, high-power laser ablation of glassy carbon in Ar atmosphere. A combination of characterization techniques revealed that the system contains both sp2 and sp3…

A zigzag graphene nanodisk can be interpreted as a quantum dot with an internal degree of freedom. It is well described by the infinite-range Heisenberg model. We have investigated its thermodynamical properties. There exists a quasi-phase…

Mesoscale and Nanoscale Physics · Physics 2009-10-06 Motohiko Ezawa

On the basis of first principles calculations, we report energy estimated to cut a graphene sheet into nanoribbons of armchair and zigzag configurations. Our calculations show that the energy required to cut a graphene sheet into zigzag…

Mesoscale and Nanoscale Physics · Physics 2013-09-12 Deepika , T. J. Dhilip Kumar , Rakesh Kumar

Dynamic magnetic properties of $\mathrm{Y_{0.7}Ca_{0.3}MnO_{3}}$ are reported. The system appears to attain local ferromagnetic order at $T_{\mathrm{SRF}} \approx 70$ K. Below this temperature the low field magnetization becomes history…

Materials Science · Physics 2009-10-31 R. Mathieu , P. Nordblad , D. N. H. Nam , N. X. Phuc , N. V. Khiem

We develop and validate a computational approach to nanomagnets. It is built on the spin wave approximation to a Heisenberg ferromagnet whose parameters can be calculated from a first principles theory (e.g. density functional theory). The…

Materials Science · Physics 2009-11-13 Michael McGuigan , James Davenport , James Glimm

Graphene nanoribbons are the counterpart of carbon nanotubes in graphene-based nanoelectronics. We investigate the electronic properties of chemically modified ribbons by means of density functional theory. We observe that chemical…

Materials Science · Physics 2009-09-29 F. Cervantes-Sodi , G. Csányi , S. Piscanec , A. C. Ferrari

Silicene is a honeycomb-structure silicon atoms, which shares many intriguing properties with graphene. Silicene is expected to be a quantum spin-Hall insulator due to its spin-orbit interactions. We investigate the electronic properties of…

Mesoscale and Nanoscale Physics · Physics 2013-10-14 Ko Kikutake , Motohiko Ezawa , Naoto Nagaosa

Theoretical study of graphite (graphene) edge is done. The most stable edge orientation is calculated to be a zigzag [110] edge. Possible applications of the result to the formation of different graphitic structures are discussed.

Materials Science · Physics 2007-05-23 Slava V. Rotkin

We study theoretically many-body properties of magic-angle twisted bilayer graphene for different doping levels. Our investigation is focused on the emergence, stability, and manifestations of nematicity of the ordered low-temperature…

Strongly Correlated Electrons · Physics 2020-10-29 A. O. Sboychakov , A. V. Rozhkov , A. L. Rakhmanov , Franco Nori

We study spin dependent transport through a magnetic bilayer graphene nanojunction configured as two dimensional normal/ferromagnetic/normal structure where the gate-voltage is applied on the layers of ferromagnetic graphene. Based on the…

Mesoscale and Nanoscale Physics · Physics 2012-11-13 Hosein Cheraghchi , Fatemeh Adinehvand

The zigzag edge of a graphene nanoribbon possesses a unique electronic state that is near the Fermi level and localized at the edge carbon atoms. We investigate the chemical reactivity of these zigzag edge sites by examining their reaction…

Chemical Physics · Physics 2007-05-23 De-en Jiang , Bobby G. Sumpter , Sheng Dai