Carbon nanotubes are composed of individual graphene sheets rolled into seamless hollow cylinders with diameters ranging from 1nm to about 20nm. The phase gives rise to resistance oscillations in a varying mag netic flux 4. Carbon nanotubes cnts are attracting tremendous interest as the object of fundamental studies in condensed matter and molecular physics as well as possible functional units for future nano devices. Aharonovbohm exciton absorption splitting in chiral speci c singlewalled carbon nanotubes in magnetic fields of up to 78 t shojiro takeyama. Specially, we consider the natural optical activity as a proper observable and derive its general expression based on a comprehensive symmetry analysis, which reveals the interplay between the enclosed magnetic flux and the tubule. We study the aharonov bohm effect in the optical phenomena of single wall carbon nanotubes swcn and also their chirality dependence.
It has also been shown that lations in semiconducting nanotubes are and can be only if nanotubes are divided into many arate regions in contrast to metallic nanotubes. The aharonovbohm effect, sometimes called the ehrenbergsidayaharonovbohm effect, is a quantum mechanical phenomenon in which an electrically charged particle is affected by an electromagnetic potential. Apr 27, 2007 aharonovbohm conductance modulation in ballistic carbon nanotubes. Aharonovbohm oscillations in carbon nanotubes core. We calculate the cross sections for inelastic light scattering by plasmons. Magnetoelectronic and optical properties of carbon nanotubes. Aharonovbohm interference and beating in singlewalled. The quantum conductance of the electron interferometers composed of the armchair and metallic zigzag singlewalled carbon nanotubes swnts in an axial magnetic field lower than 100 t has been studied by using the tightbinding approximation and landauerbuttiker formula. Band structure of nanotubes we calculated the onedimensional ek relation of carbon nanotube, started from quantification the twodimensional ek of the graphene sheet along the circumferential direction of the nanotube 15.
It has been shown that in dirty rings where the transport is diffusive there are, in general, two main mechanisms responsible for the temperature damping of the amplitude of ab oscillations. Combined effect of aharonovbohm effect and uniaxial strain. Aharonovbohm oscillations of resistance of perforated graphene. Some of the most striking features of cnts are related to the symmetry breaking effect of high magnetic fields threading the tube axis. Pdf when electrons pass through a cylindrical electrical conductor aligned in a magnetic field, their wavelike nature manifests itself as a periodic. Aharonovbohm oscillations in ptype gaas quantum rings. Berry phase by considering the evolution of dirac point under magnetic fields. Jul 01, 2010 read combined effect of aharonov bohm effect and uniaxial strain on quantum conductance oscillations of carbon nanotube resonators, the european physical journal b condensed matter and complex systems on deepdyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips. Furthermore, a recent farinfrared study of semiconducting nanorings revealed ab phasedependent spectral features 5. Heiblum braun center for submicron research, department of condensed matter physics, weizmann institute of science, rehovot 76100, israel.
The effect can manifest itself in infrared absorption and in raman scattering. Physica b 201 1994 349352 aharonov bohm effect in carbon nanotubes hiroshi ajiki, tsuneya ando institute for solid state physics, university of tokyo, 7221 roppongi, minatoku, tokyo 106, japan abstract optical absorption spectra are calculated in carbon nanotubes in the presence of a magnetic flux parallel to the tube axis. To understand the phaseshift of the ab effect in cd 3 as 2 nanowires, we would like to discuss the origin of the additional. Aharonovbohm effect in carbon nanotubes sciencedirect. Electron transport in carbon nanotubes shaun ard physics 672 nanotubes. Optical absorption spectra are calculated in carbon nanotubes in the presence of a magnetic flux parallel to the tube axis. We examine electrical and coupled electromechanical properties of multiwall carbon nanotubes using transport measurements performed insitu inside a high resolution transmission electron microscope tem. Anomalous aharonovbohm gap oscillations in carbon nanotubes. Aharonovbohm oscillations in a quasiballistic three. Magnetoelectronic and optical properties of carbon nanotubes are, respectively, studied within the sp3 tightbinding model and the gradient approximation. Curvature effects and electronic density spilled out of the nanotube surface are shown to break the periodicity of the gap oscillations.
Nano idea open access thermoelectric effect in an aharonov. Theory of the aharonovbohm effect in carbon nanotubes tsuneya ando department of physics, tokyo institute of technology, 2121 ookayama, meguroku, tokyo 1528551, japan abstract. Aharonovbohm oscillations in phosphorene quantum rings l. Carbon nanotubes are chemically derived cylinders with atomically wellde. These oscillations have been observed in various metallic rings and tubes, including the recent observation of the aas oscillations in multiwalled carbon nanotubes. Aug 01, 2011 the gap oscillations caused by a magnetic flux penetrating a carbon nanotube represent one of the most spectacular observations of the aharonovbohm effect at the nanoscale. In some nanotubes we also observe shorterperiod oscillations, which might result from anisotropic electron cur rents caused by defects in the nanotube lattice.
Carbon nanotubes are composed of individual graphene sheets rolled into seamless hollow cylinders with diameters ranging from 1 nm to about 20 nm. The present volume builds on the generic aspects of the aforementioned book, which emphasizes the. Shaping electron wave functions in a carbon nanotube with a. Carbon nanotubes 9,10 are composed of individual graphene sheets rolled. They are able to act as conducting molecular wires, making them ideally suited for the investigation of quantum interference at the singlemolecule level caused by the aharonovbohm effect. Using an abinitio approach based on density functional theory we show that this assumption fails at the nano scale inducing important corrections to the physics of the aharonovbohm effect. The amplitude of the he oscillations increases with vdc once the thouless energy ec and thermal.
The flux quantization in the nanotube leads to magne toresistance oscillations as the longitudinal magnetic field increases the aharonovbohm effect. When electrons pass through a cylindrical electrical conductor aligned in a magnetic field, their wavelike nature manifests itself as a periodic oscillation in the electrical resistance as a. Lassagne b1, cleuziou jp, nanot s, escoffier w, avriller r, roche s, forro l, raquet b, broto jm. In the introduction part of the thesis, a brief summary about carbon nanotubes is given. The gap oscillations caused by a magnetic flux penetrating a carbon nanotube represent one of the most spectacular observation of the aharonovbohm effect at the nano scale. Aharonovbohm oscillations by changing the voltage applied to the side gate. In presence of some mode mixing they result in fano resonances that are characterized by a zeropole pair 7. The higherorder oscillation peaks with magnetic flux exist in the mr can also be. Beside the he oscillations, we resolve the contributions from higher harmonics of the ab oscillations. Reymonta 4, pl30059 krakow, poland the conductance of an aharonovbohm interferometer is. We here describe the successful engineering of multiwalled carbon nanotubes into idealgeometry tips for scanned probe microscopy, field emission, or biological insertion applications, as well as the construction of apparently wearfree linear nanobearings and constantforce nanosprings.
Theory of transport in carbon nanotubes tokyo tech condensed. Aharonovbohm oscillations in carbon nanotubes nasaads. In this experiment, the visibility of the aharonovbohm. Effect of quantum entanglement on aharonovbohm oscillations, spinpolarized transport and current magni. The results are associated with the existence of the tammtype states of the dirac electrons tammdirac states theory.
The carbon nanotubes field has evolved substantially since the publication of the bestseller carbon nanotubes. Conductivity in carbon nanotubes with aharonov bohm flux takeshi nakanishi and tsuneya ando1 national institute of advanced industrial science and technology 1 umezono, tsukuba 3058568, japan and crest, jst 418 honmachi, kawaguchi, saitama 3320012 japan 1department of physics, tokyo institute of technology. Abstract the carbon tori and nanotubes, either pure or holedoped, are examined. In this thesis, persistent currents in carbon nanotubes is investigated. This is shown to be consistent wirh aharonov bohm oscillations 26 of the bandgap due to a flux.
The aharonovbohm interference and beating in single. In threedimensional topological insulator nanowires, they can be used to not only. Romanovsky, and uzi landman school of physics, georgia institute of technology, atlanta, georgia 303320430, usa. Transport, aharonovbohm, and topological effects in. Resistance of nano perforated graphene samples demonstrate the aharonovbohm typemagnetooscillation with period corresponding to the flux quantum per hole area. In the presence of a magnetic field parallel to the tube axis, the plasmon frequencies undergo aharonov bohm oscillations. A schematic diagram of the aharonov bohm ring with a delta function potential at site x is shown in fig.
Excitons in metallic carbon nanotubes with aharonovbohm. Chiral effects in normal and superconducting carbon nanotubebased nanostructures. Aharonovbohm oscillations in dirac semimetal cd3as2 nanowires. In the presence of a magnetic field parallel to the tube axis, the plasmon frequencies undergo aharonovbohm oscillations. We give a multiplecycle quantum interference model and obtain magnetoresistance mr expression in the framework of the weak localization. Aharonovbohm oscillations in phosphorene quantum rings. Aharonovbohm oscillations of a tuneable quantum ring. Chiral effects in normal and superconducting carbon. Theory scanning tunneling microscopy stm nanotube contacts. Combined effect of aharonovbohm effect and uniaxial.
We have observed 3 frequencies of the mr oscillations. The phase gives rise to resistance oscillations in a varying magnetic flux 4. When electrons pass through a cylindrical electrical conductor aligned in a magnetic field, their wavelike nature manifests itself as. The gap oscillations caused by a magnetic flux penetrating a carbon nanotube represent one of the most spectacular observation of the aharonovbohm effect at.
Phase rigidity and h2e oscillations in a singlering aharonov bohm experiment a. Nano idea open access thermoelectric effect in an aharonovbohm ring with an embedded quantum dot jun zheng1, feng chi2, xiaodong lu2 and kaicheng zhang3 abstract thermoelectric effect is studied in an aharonovbohm interferometer with an embedded quantum dot qd in the coulomb blockade regime. Plasma oscillations in nanotubes and the aharonovbohm. Quantum interference of electrons in multiwall carbon nanotubes. Naturevolume 397, pages673675 1999 download citation.
Chiral effects in normal and superconducting carbon nanotube. We report measurements of the amplitude of the aharonovbohm oscillations in a mesoscopic diffusive gold ring as a function of the dc bias voltage vdc. The gap oscillations caused by a magnetic flux penetrating a carbon nanotube represent one of the most spectacular observations of the aharonovbohm effect at the nanoscale. Patterns of the aharonovbohm oscillations in graphene. Highly visible aharonov bohm ab oscillations are measured in both rings, with an amplitude of the oscillations exceeding 10% of the total resistance in the case of the ring with a radius of 160 nm. The mr expression based upon finite phasebreaking length l. A hallmark of the aharonovbohm ab effect 1 is conductance oscillations of metallic rings or cylinders as a function of enclosed magnetic.
Only recently, the aharanovbohm effect has been observed for the. Aharonov bohm interference and beating in singlewalled carbon nanotube interferometers jien cao, qian wang, marco rolandi, and hongjie dai department of chemistry and laboratory for advanced materials, stanford university, stanford, ca 94305, usa. Also in carbon nanotubes cnts, the electronic wave function acquires an. We present a simple model of transmission across a metallic mesoscopic ring.
Peeters1 1department of physics, university of antwerp, groenenborgerlaan 171, b2020 antwerpen, belgium 2key laboratory of materials physics, institute of solid state physics, chinese academy of sciences, hefei 230031, china. We study the aharonovbohm effect in the optical phenomena of single wall carbon nanotubes swcn and also their chirality dependence. Aharonovbohm effect in carbon nanotubes hiroshi ajiki, tsuneya ando institute for solid state physics, university of tokyo, 7221 roppongi, minatoku, tokyo 106, japan abstract optical absorption spectra are calculated in carbon nanotubes in the presence of a magnetic flux parallel to the tube axis. Properties and applications depending on the strength of the applied. Specially, we consider the natural optical activity as a proper observable and derive its general expression based on a comprehensive symmetry analysis, which reveals the interplay between the enclosed magnetic flux and the tubule chirality for arbitrary. Aharonovbohm oscillations in carbon nanotubes nature. Also in carbon nanotubes cnts, the electronic wave function acquires an aharonovbohm phase when a magnetic field is applied along. In the ballistic mode, the period of oscillations in the flux is ce 6, 7. When electrons pass through a cylindrical electrical conductor aligned in a.
Aharonovbohm conductance modulation in ballistic carbon. Theory of the aharonov bohm effect in carbon nanotubes tsuneya ando department of physics, tokyo institute of technology, 2121 ookayama, meguroku, tokyo 1528551, japan abstract. A hallmark of the aharonovbohm ab effect 1 is conductance oscillations of. Aharonov bohm oscillations in ptype gaas quantum rings. Aharonovbohm oscillations effectively demonstrate coherent, ballistic transport in mesoscopic rings and tubes. Conductivity in carbon nanotubes with aharonovbohm flux. The tuning via inplane gates allows one to study the aharonovbohm effect in the whole range from the open ring to the coulombblockade regime. Optical signatures of the aharonovbohm phase in single. Evidence for dark excitons in a single carbon nanotube due to. The higherorder oscillation peaks with magnetic flux. The equidistant oscillations of the mr have been observed in a wide range of magnetic fields up to 14 t at various temperatures and angles. Bulk and end connected coulomb blockade coulomb blockade only. We predict the key phenomenological features of this anomalous aharonovbohm effect in semiconductive and met allic tubes and the existence of a large metallic phase in the low. Interplay of bandstructure and quantum interference in.
Phase rigidity and h2e oscillations in a singlering. Electromechanical properties of multiwall carbon nanotubes. Aharonov bohm effect and plasma oscillations in superconducting tubes and rings e. They strongly depend on the magnitude and the direction of the magnetic. The unique ultrarelativistic, massless, nature of electron states. Bohm oscillations of the magnetoresistance mr of single.
Plasma oscillations in nanotubes and the aharonovbohm effect. Read combined effect of aharonovbohm effect and uniaxial strain on quantum conductance oscillations of carbon nanotube resonators, the european physical journal b condensed matter and complex systems on deepdyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips. Temperature dependence of the aharonovbohm oscillations and. In the following we show that across the zeros of this resonance the phase of aharonov bohm oscillations will change by 7r. He demonstrated electronic quantum interference by measuring the aharonovbohm effect in multiwalled carbon nanotubes and by realizing the quantum optical hanbury brown and twiss effect for the first time with electrons and demonstrated the antibunching effects arising from their fermionic statistics and he demonstrated electron transport. Carbon nanotubes are novel quantum wires consisting of rolled graphite sheets. Physica b 201 1994 349352 aharonovbohm effect in carbon nanotubes hiroshi ajiki, tsuneya ando institute for solid state physics, university of tokyo, 7221 roppongi, minatoku, tokyo 106, japan abstract optical absorption spectra are calculated in carbon nanotubes in the presence of a magnetic flux parallel to the tube axis. As first noticed by aharonov and bohm 1, when a charged quantum.
Present research on topological insulators is still at an early stage, but has the potential to have a bright future. This giant aharonovbohm ab effect on the bandgap is a unique property of cns. In the two achiral zigzag and armchair systems the momentum lines are parallel to the edges of the brillouin zone or the 3. When electrons pass through a cylindrical electrical conductor aligned in a magnetic field, their wavelike nature manifests itself as a periodic.
Aharonovbohm oscillations and electron gas transitions in hexagonal coreshell nanowires with an axial magnetic. Transport measurements in the open regime show only one transmitting mode and aharonovbohm oscillations with more than 50% modulation are observed in the conductance. Carbon nanotubes are one of the most important and interesting subjects of the nanotechnology. Theory of the aharonovbohm effect in carbon nanotubes. We theoretically analyze the collective oscillations of 2d electrons in nanotubes. Our understanding of this effect is, however, based on the assumption that the electrons are strictly confined on the tube surface, on trajectories that are not modified by curvature effects. The gap oscillations caused by a magnetic flux penetrating a carbon nanotube represent one of the most spectacular observations of the aharonov bohm effect at the nanoscale. Ii we introduce the new concept of chiral tunneling in metallic swnts. Aharonovbohm oscillations and electron gas transitions in. Effect of quantum entanglement on aharonovbohm oscillations. Aharonovbohm exciton absorption splitting in chiral speci. Magneto spectroscopy of singlewalled carbon nanotubes. Highly visible aharonovbohm ab oscillations are measured in both rings, with an amplitude of the oscillations exceeding 10% of the total resistance in the case of the ring with a radius of 160nm.
251 979 1326 129 1524 1252 899 437 1559 1365 231 1453 820 1233 761 560 1515 771 1466 968 1622 234 1094 308 810 1275 1605 273 577 1289 1215 1039 38 75 750 364 1249