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arXiv 1906.02553cond-mat.str-el
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近藤系统的扫描隧道散粒散粒噪声谱

Scanning Tunneling Shot Noise Spectroscopy in Kondo Systems

Sagen Cocklin, Dirk K. Morr

摘要:

使用大N理论与Keldysh非平衡格林函数形式主义相结合,我们调查的电流,微分电导,零频散粒噪声和Fano因子测量扫描隧道散粒噪声光谱(STSNS)使用扫描隧道显微镜(STM)附近的单个近藤杂质和近藤晶格。我们发现,Fano因子$F$表现出的特征偏置依赖所产生的近藤屏蔽,这是类似的近藤共振中观察到的微分电导。此外,$F$的线形强烈依赖于电子从STM针尖隧穿到导带的隧穿幅度与磁性吸附原子的电子能级的比值。我们证明,Fano因子可以增强或抑制由于干涉效应,因此,不仅是一个敏感的探针的相关效应所产生的近藤屏蔽,但也隧道电子之间的量子干涉。我们确定的微分电导和Fano因子,可以在未来的STSNS实验中进行测试的形式之间的相关性。

英文摘要:

Using a large-N theory in combination with the Keldysh non-equilibrium Greens function formalism, we investigate the current, differential conductance, zero-frequency shot-noise and Fano factor as measured by scanning tunneling shot noise spectroscopy (STSNS) using a scanning tunneling microscope (STM) near single Kondo impurities and in Kondo lattices. We show that the Fano factor $F$ exhibits a characteristic bias dependence arising from Kondo screening that is similar to the Kondo resonance observed in the differential conductance. Moreover, the lineshape of $F$ is strongly dependent on the ratio of the tunneling amplitudes for electron tunneling from the STM tip into the conduction band and electronic levels of the magnetic adatoms. We demonstrate that the Fano factor can be enhanced or suppressed due to interference effects and as such, is not only a sensitive probe for the correlation effects arising from Kondo screening, but also for quantum interference between tunneling electrons. We identify a correlation between the form of the differential conductance and the Fano factor that could be tested in future STSNS experiments.

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