Giant magnetoresistance of multiwall carbon nanotubes: Modeling the tube/ferromagnetic-electrode burying contact

Krompiewski, S.; Gutiérrez, Rafael

doi:10.1103/physrevb.69.155423

Cited by 32 publications

(31 citation statements)

References 27 publications

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“…In my previous papers, very special geometries of the SWCNT (6,6) armchair and the double-walled CNT (2,2)@(6,6) were studied (see [18] - [20] for details). In those cases it was possible to construct the end-contacted devices in such a way that interface carbon atoms were placed exactly above the centers of equilateral triangles formed by the adjacent transition metal atoms.…”

Section: Modelling Of the Devices And The Resultsmentioning

confidence: 99%

“…The Green's function technique has been used, along the line of the non-equilibrium transport formalism, and under constraint of global charge neutrality. The so-called extended molecule concept is adapted, by incorporating to the central part of the system not only the entire molecule (CNT) but also two closest magnetic atomic planes from the left-and right-hand side electrodes [20]. The Green's function is defined as G = (1E − H C − Σ L − Σ R ) −1 , whereas the density matrix of electrons and current (per spin) are given by:…”

Section: Theoretical Approachmentioning

confidence: 99%

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Spin‐polarized transport through carbon nanotubes

Krompiewski

2005

Physica Status Solidi (b)

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Published online zzz PACS 85.35. Kt, 81.07.De, Carbon nanotubes (CNT) belong to the most promising new materials which can in the near future revolutionize the conventional electronics. When sandwiched between ferromagnetic electrodes, the CNT behaves like a spacer in conventional spin-valves, leading quite often to a considerable giant magneto-resistance effect (GMR). This paper is devoted to reviewing some topics related to electron correlations in CNT. The main attention however is directed to the following effects essential for electron transport through nanotubes: (i) nanotube/electrode coupling and (ii) inter-tube interactions. It is shown that these effects may account for some recent experimental reports on GMR, including those on negative (inverse) GMR.Copyright line will be provided by the publisher 1 Introduction A particularly challenging class of materials for the future electronics are carbon nanotubes, i.e. graphite sheets rolled up in such a manner that they form very long and thin (in atomic scale) cylinders. Their length can be of the order of several micrometers whereas typical cross-sections of single wall carbon nanotubes (SWCNT) are a few nanometers in diameter, and roughly up to 10 times more for multi-wall carbon nanotubes (MWCNT) . Both the SWCNTs and MWCNTs have been attracting much attention of many researchers since they were discovered [1].It is now clear that the electronics based on conventional semiconducting devices (e.g. silicon technology) has faced fundamental limitations as far as further miniaturization is concerned. The reasons are various, including the fact that the relative amount of surface states -destructive for electronic transport properties -increases rapidly in 2-and 3-dimensional systems when their sizes are being reduced. Likewise, it is predicted that the SiO 2 layer in the MOSFET will be too thin soon (within 10 years or so) to retain its insulating properties [2]. So, there is much interest of physicists, technologists and engineers in new generation nano-scale devices, including molecular ones. The adopted approach is the so-called bottom up philosophy, aiming at designing electronic devices at the molecular level. In contrast to siliconbased devices, the molecular ones (incl. carbon nanotubes, CNT) can successfully cope with the more and more demanding miniaturization requirements without worsening their multi-functional properties. Most probably the CNTs are also good candidates for spintronics applications in view of their unusually long spin diffusion length. It is well-known that electrons can travel through carbon nanotubes up to many hundreds of nanometers, still keeping their momentum and spin orientation. So CNTs are believed to be useful in the near future microelectronics (or molecular electronics) as interconnects, and possibly also as active elements in integrated circuits. Physical properties of the CNTs connected to metallic electrodes depend critically on a quality of CNT/metal junctions, and may evolve with increasing transparencies of the j...

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Section: Modelling Of the Devices And The Resultsmentioning

confidence: 99%

Section: Theoretical Approachmentioning

confidence: 99%

Spin‐polarized transport through carbon nanotubes

Krompiewski

2005

Physica Status Solidi (b)

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“…This is very different from magnetotransport through finite CNTs: Scattering at the contacts leads to resonant tunneling, resulting in spectroscopy of the electronic states of the finite tube. 39,40 This spectrum may show strong dependence on magnetic fields, even in regions of flat bands, 16 resulting in quantum-dot-like physics. 41 Relation to 2D periodic structures.…”

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confidence: 99%

Hofstadter butterflies of carbon nanotubes: Pseudofractality of the magnetoelectronic spectrum

Nemec

Cuniberti

2006

Phys. Rev. B

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The electronic spectrum of a two-dimensional square lattice in a perpendicular magnetic field has become known as the Hofstadter butterfly ͓Hofstadter, Phys. Rev. B 14, 2239 ͑1976͒.͔. We have calculated quasi-onedimensional analogs of the Hofstadter butterfly for carbon nanotubes ͑CNTs͒. For the case of single-wall CNTs, it is straightforward to implement magnetic fields parallel to the tube axis by means of zone folding in the graphene reciprocal lattice. We have also studied perpendicular magnetic fields which, in contrast to the parallel case, lead to a much richer, pseudofractal spectrum. Moreover, we have investigated magnetic fields piercing double-wall CNTs and found strong signatures of interwall interaction in the resulting Hofstadter butterfly spectrum, which can be understood with the help of a minimal model. Ubiquitous to all perpendicular magnetic field spectra is the presence of cusp catastrophes at specific values of energy and magnetic field. Resolving the density of states along the tube circumference allows recognition of the snake states already predicted for nonuniform magnetic fields in the two-dimensional electron gas. An analytic model of the magnetic spectrum of electrons on a cylindrical surface is used to explain some of the results.

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“…[19][20][21][22][23][24][25] Further theoretical studies [26][27][28][29] reveal that the transport properties are directly related to the magnetic-field modulated density of states. The SOI-modified band structure and its implications on the electronic properties of CNT's in a magnetic field have been in the focus of extensive theoretical work.…”

Section: Introductionmentioning

confidence: 99%

Signatures of spin-orbit interaction in transport properties of finite carbon nanotubes in a parallel magnetic field

2011

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The transport properties of finite nanotubes placed in a magnetic field parallel to their axes are investigated. Upon including spin-orbit coupling and curvature effects, two main phenomena are analyzed that crucially depend on the tube's chirality: (i) Finite carbon nanotubes in a parallel magnetic field may present a suppression of current due to the localization at the edges of otherwise conducting states. This phenomenon occurs due to the magnetic-field-dependent open boundary conditions obeyed by the carbon nanotube's wave functions. The transport is fully suppressed above threshold values of the magnetic field, which depend on the nanotube chirality, length, and on the spin-orbit coupling. (ii) Reversible spin-polarized currents can be obtained upon tuning the magnetic field, exploiting the curvature-induced spin-orbit splitting.

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Giant magnetoresistance of multiwall carbon nanotubes: Modeling the tube/ferromagnetic-electrode burying contact

Cited by 32 publications

References 27 publications

Spin‐polarized transport through carbon nanotubes

Spin‐polarized transport through carbon nanotubes

Hofstadter butterflies of carbon nanotubes: Pseudofractality of the magnetoelectronic spectrum

Signatures of spin-orbit interaction in transport properties of finite carbon nanotubes in a parallel magnetic field

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