Theoretical studies of spin-dependent electrical transport through carbon nanotubes
Theoretical studies of spin-dependent electrical transport through carbon nanotubes
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碳纳米管自旋相关电传输的理论研究
DOI：
10.1088/0268-1242/21/11/s12
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发表时间：
2006
影响因子：
1.9
通讯作者：
S. Krompiewski
中科院分区：
文献类型：
--
作者：
S. Krompiewski
利用紧束缚模型和绿色函数分配技术，对碳纳米管中自旋相关的相干量子输运进行了理论研究。端部接触的金属/纳米管/金属系统建模，并在磁性的背景下，即，无论是与铁磁电极或在外部磁场中的下一个研究。前一种情况表明，相当可观的巨磁电阻（GMR）效应发生（±20%）的无序碳纳米管。安德森-无序平均GMR，反过来，是积极的，并降低到几个百分点附近的电荷中性点。在平行的磁场中，特征Aharonov-Bohm型振荡被揭示出具有显著的特征，这是由于以下因素的综合作用：长度周长比、无意的电极诱导掺杂、塞曼分裂和能级加宽。特别地，预测CNT在其长度和周长变得相当时将失去其充当磁电开关的能力。在垂直几何形状的情况下，存在渐近接近电导的理论上限4 e2/h的电导振荡。此外，在弹道输运制度，最初的电导增加，只有轻微的磁场或保持几乎恒定，因为自旋向上和自旋向下的贡献，总磁阻部分相互补偿。
Spin-dependent coherent quantum transport through carbon nanotubes (CNT) is studied theoretically within a tight-binding model and the Green 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 in external magnetic fields. The former case shows that quite a substantial giant magnetoresistance (GMR) effect occurs (±20%) for disorder-free CNTs. Anderson-disorder averaged GMR, in turn, is positive and reduced down to several per cent in the vicinity of the charge neutrality point. In 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 the case of perpendicular geometry, there are conductance oscillations approaching asymptotically the upper theoretical limit to the conductance, 4e2/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.
影响因子：
8.6
作者：
Tanaka, M;Higo, Y
通讯作者：
Higo, Y