Engineering a topological quantum dot device through planar magnetization in bismuthene

Abstract

The discovery of quantum spin Hall materials with huge bulk gaps in experiment, such as bismuthene, provides a versatile platform for topological devices. We propose a topological quantum dot (QD) device in bismuthene ribbon in which two planar magnetization areas separate the sample into a QD and two leads. At zero temperature, peaks of differential conductance emerge, demonstrating the discrete energy levels from the confined topological edge states. The key parameters of the QD, the tunneling coupling strength with the leads and the discrete energy levels, can be controlled by the planar magnetization and the sample size. Specially, different from the conventional QD, we find that the angle between two planar magnetization orientations provides an effective way to manipulate the discrete energy levels. Combining the numerical calculation and the theoretical analysis, we identify that such manipulation originates from the unique quantum confinement effect of the topological edge states. Based on such mechanism, we find the spin transport properties of QDs can also be controlled.

Coherent spin transport through helical edge states of topological insulator

“…We will limit ourselves to the discussion of non-interacting electrons focusing on the high-temperature cases. For discussion of spin polarization in the case of the low temperature, see refs [62][63][64][65][66] , while interaction-induced 67 and quantum pumping generated 68 spin currents were considered for Fabry-Pérot geometry at ϕ = 0. We will demonstrate that the finite polarization appears even in the fully classical regime and therefore robust to dephasing.…”

Transport properties of Hall-type quantum states in disordered bismuthene

“…Nevertheless, owing to the weak spin-orbit coupling of graphene, the tiny bulk gap is only about 40 µeV, limiting its applica-tion for quantum devices. [23] Subsequently, the graphenelike structures with a strong spin-orbit coupling, such as arsenene, [24,25] antimonene, [26][27][28][29] bisthumene, [30][31][32][33][34][35] transition metal dichalcogenides, [36][37][38] are investigated. Remarkably, the bismuthene on SiC substrate has a huge topological bulk gap, [30] rendering the application of quantum devices feasible.…”

Interference effect in the electronic transport of a topological insulator quantum dot

“…Numerical studies indicate that surface states are still robust against disorder in a TIQD [6]. Unique electronic [4][5][6][7][8][9][10][11][12][13][14][15][16][17] and optical properties [18][19][20][21][22] due to surface levels have been predicted and potential applications suggested [23][24][25][26][27]. For the moment, QDs of Bi 2 Se 3 [28][29][30] and Bi 2 Te 3 [31] have been fabricated experimentally.…”