在二維的模型下，奈米碳管的導電是經由表面pi電子雲的共振，其傳輸為等向性（isotropic）。但在三維的模型下，pi電子雲於費米能階的波函數是延著2Pz軸延伸約1 À，因此，碳管表面之波函數可分為二個分量，即平行管軸向之Jz與沿管圓周向之Jc分量。如於平行管軸的方向施加一電場，則沿管圓周向之Jc分量會被電場驅使而產生些許偏轉，此偏轉使Jc電流以螺旋形狀沿著碳管壁的圓周流動，類似線圈 （solenoid）。如果奈米碳管內包覆具鐵磁性的金屬，此包覆金屬的奈米碳管即成為一奈米電磁線圈。至今，關於奈米碳管內磁場的研究仍然缺乏，亦無直接的證據證實奈米碳管表面具螺旋形狀的電流與電感性（inductive phase），本實驗以快速且經濟（不需利用高價儀器）的方式，將單束含鐵奈米碳管懸空架橋於兩電極之間，通以交流電進行量測，成功地測得含鐵奈米碳管的電感值，此電感值的大小及數量級為mH，間接證明了碳管表面的螺旋電流。

Carbon nanotubes（CNTs）are graphene sheets rolled up into cylindrical structure and electron transport via tube surface lattice is essentially isotropic. This description is based on a 2D lattice model. In a 3D approach, electron wave function near to the Fermi level is extended by 1 Å along the 2Pz orbit and electron transport thus becomes sensitive to electron field. Reports indicate two possible paths of charge carrier in a small CNT, i.e. along tube axis and circumference. When electric field is applied in parallel with tube axis the electron flux along circumference is diverted into a helix current, similar to nano-coils. This spiral current becomes apparent when angular frequency is smaller than stark frequency in an AC field.
To date, explore of magnetic field within a CNT remains as challenge and a straightforward verification is to encapsulate magnetic materials in CNTs so interior magnetic field is enhanced and becomes measurable. In this work, individual Fe-encapsulated CNTs bridging tungsten electrodes are verified and measured by AC impedance technique. Inductance at different frequency is detected and is on the order of mH.

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