Theoretical studies of spin-dependent electrical transport through carbon nanotbes

Abstract

Spin-dependent coherent quantum transport through carbon nanotubes (CNT) is studied theoretically within a tight-binding model and the Green's function partitioning technique. End-contacted metal/nanotube/metal systems are modelled and next studied in the magnetic context, i.e. either with ferromagnetic electrodes or at external magnetic fields. The former case shows that quite a substantial giant magnetoresistance (GMR) effect occurs ($\pm 20$) for disorder-free CNTs. Anderson-disorder averaged GMR, in turn, is positive and reduced down to several percent in the vicinity of the charge neutrality point. At parallel magnetic fields, characteristic Aharonov-Bohm-type oscillations are revealed with pronounced features due to a combined effect of: length-to-perimeter ratio, unintentional electrode-induced doping, Zeeman splitting, and energy-level broadening. In particular, a CNT is predicted to lose its ability to serve as a magneto-electrical switch when its length and perimeter become comparable. In case of perpendicular geometry, there are conductance oscillations approaching asymptotically the upper theoretical limit to the conductance, $4e^2/h$. Moreover in the ballistic transport regime, initially the conductance increases only slightly with the magnetic field or remains nearly constant because spin up- and spin down-contributions to the total magnetoresistance partially compensate each other.

arXiv comment15 pages, 6 figures (to apppear in Semicond. Sci. Technol.)

References in corpus (12)

• Spintronics: Fundamentals and applications
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• Electrical Spin Injection in Multi-Wall carbon NanoTubes with transparent ferromagnetic contacts
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• Schottky barriers at metal-finite semiconducting carbon nanotube interfaces
• Spin-polarized transport through carbon nanotubes
• Suitability of carbon nanotubes grown by chemical vapor deposition for electrical devices
• Spin transport in disordered single-wall carbon nanotubes contacted to ferromagnetic leads
• Effect of Contact Interfaces on Quantum Conductance of Armchair Nanotubes

Cited by in corpus (4)

• Theoretical studies of spin-dependent electronic transport in ferromagnetically contacted graphene flakes
• Transport through single-wall metallic carbon nanotubes in the cotunneling regime
• Theory of shot noise in single-walled metallic carbon nanotubes weakly coupled to nonmagnetic and ferromagnetic leads
• Modeling a Schottky-barrier carbon nanotube field-effect transistor with ferromagnetic contacts