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arXiv · 1811.00750

Splitting of conductance resonance through a magnetic quantum dot in graphene

Nojoon Myoung·Jung-Wan Ryu·Hee Chul Park·Seung Joo Lee·Sungjong Woo
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Abstract

We report a dual resonance feature in ballistic conductance through a quantum Hall graphene nanoribbon with a magnetic quantum dot. Such a magnetic quantum dot localizes Dirac fermions exhibiting anisotropic eigenenergy spectra with broken time-reversal symmetry. Interplay between the localized states and quantum Hall edge states is found to be two-fold, showing Breit-Wigner and Fano resonances, which is reminiscent of a double quantum dot system. By fitting the numerical results with the Fano-Breit-Wigner lineshape from the double quantum dot model, we demonstrate that the two-fold resonance is due to the valley mixing that comes from the coupling of the magnetic quantum dot with quantum Hall edge channels; an effective double quantum dot system emerges from a single magnetic quantum dot in virtue of the valley degree of freedom. It is further confirmed that the coupling is weaker for the Fano resonance and stronger for the Breit-Wigner resonace.

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Nojoon Myoung, Jung-Wan Ryu, Hee Chul Park, Seung Joo Lee, Sungjong Woo. 2018-11-02. Splitting of conductance resonance through a magnetic quantum dot in graphene. https://doi.org/10.1103/physrevb.100.045427

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