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arXiv 1002.2215cond-mat.str-elcond-mat.mes-hall
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石墨烯中的门控近藤屏蔽:量子临界性和电子空穴不对称性

Gate-controlled Kondo screening in graphene: Quantum criticality and electron-hole asymmetry

Matthias Vojta, Lars Fritz, Ralf Bulla

摘要:

中性石墨烯中的磁性杂质提供了赝能隙Kondo模型的实现,该模型显示了具有屏蔽杂质矩和未屏蔽杂质矩的相之间的量子相变。在这里,我们提出了一个详细的研究pseudogap Kondo模型与有限的化学势μ。虽然载流子掺杂在最低能量下恢复了传统的近藤屏蔽,但量子临界固定点的性质在很大的参数范围内会影响行为。最重要的是,近藤温度T_K显示了电子和空穴掺杂之间的极端不对称性。在临界状态下,取决于μ的符号,T_K遵循具有通用前因子的缩放预测T_K ~ |mu|,或者遵循具有x = 2.6的T_K ~ |mu| ^x。电子和空穴掺杂之间的这种不对称性在量子临界区之外延伸得很好,并且还意味着μ的两个符号的隧穿光谱的形状的质的差异。

英文摘要:

Magnetic impurities in neutral graphene provide a realization of the pseudogap Kondo model, which displays a quantum phase transition between phases with screened and unscreened impurity moment. Here, we present a detailed study of the pseudogap Kondo model with finite chemical potential mu. While carrier doping restores conventional Kondo screening at lowest energies, properties of the quantum critical fixed point turn out to influence the behavior over a large parameter range. Most importantly, the Kondo temperature T_K shows an extreme asymmetry between electron and hole doping. At criticality, depending on the sign of mu, T_K follows either the scaling prediction T_K ~ |mu| with a universal prefactor, or T_K ~ |mu|^x with x = 2.6. This asymmetry between electron and hole doping extends well outside the quantum critical regime and also implies a qualitative difference in the shape of the tunneling spectra for both signs of mu.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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