Kondo effect in a topological insulator quantum dot

Abstract

We investigate the non-equilibrium transport properties of a topological insulator quantum dot (TIQD) in the Coulomb blockade and Kondo regime theoretically. An Anderson impurity model is applied to a TIQD system coupled to two external leads, and we show that the model realizes the spin-orbital Kondo effect at Dirac point where the edge states are not split by a finite-size effect, leading to an additional SU (4) symmetry because of the presence of strong mixture among four internal degrees of freedom. In a more realistic situation where the degeneracy is lifted due to the finite-size effect, we demonstrate that there is a richer structure in transport measurements. We illustrate a continuous crossover from four (spin and orbital) Coulomb peaks with large inter-pair spacing and small intra-pair spacing to a double-peak structure in the local density of states (LDOS) as increasing the hybridization strength Γ within the Coulomb blockade regime. When temperature falls below the Kondo temperature TK , four Kondo peaks show up in the non-equilibrium LDOS. Two of them are located at the chemical potential of each lead, and the other two are shift away from the chemical potential by the amount proportional to the TIQD's bare energy level, leading to a triple-peak structure in the differential conductance when a bias voltage is applied.

Low-energy electronic properties of a Weyl semimetal quantum dot

“…The case of B = −5T is similar with the B = 5T case, with eigenenergy and j z reversed due to the P symmetry given in Eq. (42). Besides, we also notice that there is a dip and hump structure connected to the flat energy band in Fig.…”

Quantum spin compass models in 2D electronic topological metasurfaces

“…The electronic spectrum of such a system was obtained in Refs. [22,23] and associated quantum impurity models have been considered in a number of follow up works [24,25].…”

A Single‐Electron Transistor Made of a 3D Topological Insulator Nanoplate

“…This work provides a controllable and reproducible way to form quantum confined systems in three-dimensional topological insulators, which should greatly stimulate research towards confined topological states, low energy-dissipative devices and quantum information processing.Topological insulators (TIs), which exhibit time-reversal symmetry (TRS) protected and spin-momentum inter-locked gapless Dirac surface states in the bulk band gap, are a new class of quantum matters. [1,2] Quantum confined TI devices have been proposed to be promising and of great importance for studies of the fundamental physics of confined topological states [3][4][5][6][7][8] and for applications in low energy-dissipative spintronics [9][10][11] and quantum information processing [12][13][14] . However, the absence of energy gap at the Dirac surface states and the related Klein tunneling phenomenon make it impossible to confine electrons electrostatically and to control the transport on the level of single electron via gating confinement.…”