Maciel Indhira O, Anderson Neil, Pimenta Marcos A, Hartschuh Achim, Qian Huihong, Terrones Mauricio, Terrones Humberto, Campos-Delgado Jessica, Rao Apparao M, Novotny Lukas, Jorio Ado
Departamento de Física, Universidade Federal de Minas Gerais, Belo Horizonte, MG, 30123-970, Brazil.
Nat Mater. 2008 Nov;7(11):878-83. doi: 10.1038/nmat2296. Epub 2008 Oct 19.
Owing to their influence on electrons and phonons, defects can significantly alter electrical conductance, and optical, mechanical and thermal properties of a material. Thus, understanding and control of defects, including dopants in low-dimensional systems, hold great promise for engineered materials and nanoscale devices. Here, we characterize experimentally the effects of a single defect on electrons and phonons in single-wall carbon nanotubes. The effects demonstrated here are unusual in that they are not caused by defect-induced symmetry breaking. Electrons and phonons are strongly coupled in sp(2) carbon systems, and a defect causes renormalization of electron and phonon energies. We find that near a negatively charged defect, the electron velocity is increased, which in turn influences lattice vibrations locally. Combining measurements on nanotube ensembles and on single nanotubes, we capture the relation between atomic response and the readily accessible macroscopic behaviour.
由于缺陷对电子和声子有影响，它们能显著改变材料的电导率以及光学、机械和热学性质。因此，对缺陷（包括低维系统中的掺杂剂）的理解和控制，对于工程材料和纳米级器件具有巨大的前景。在这里，我们通过实验表征了单壁碳纳米管中单个缺陷对电子和声子的影响。此处展示的效应很不寻常，因为它们并非由缺陷诱导的对称性破缺引起。在sp(2)碳系统中，电子和声子强烈耦合，一个缺陷会导致电子和声子能量的重整化。我们发现，在带负电荷的缺陷附近，电子速度会增加，这反过来又会局部影响晶格振动。通过对纳米管集合体和单个纳米管的测量相结合，我们捕捉到了原子响应与易于获取的宏观行为之间的关系。
