Signature of Spin-Resolved Quantum Point Contact in p-Type Trilayer WSe₂ van der Waals Heterostructure

Abstract

In this study, the electrostatically induced quantum confinement structure, quantum point contact, has been realized in p-type trilayer tungsten diselenide-based van der Waals heterostructure with modified van der Waals contact method with degenerately doped transition metal dichalcogenide crystals. Clear quantized conductance and pinch-off state through the onedimensional confinement were observed by dual-gating of split gate electrodes and top gate.Conductance plateaus were observed at step of 0.5  2 e 2 /h at zero and high magnetic field in addition to quater plateaus at a finite bias voltage condition indicating the intrinsic spin-polarized quantum point contact realization.

Anomalous conductance quantization of a one-dimensional channel in monolayer WSe2

“…This is surprising since in monolayer TMDs, due to spinvalley locking, we expect conductance quantization for non-interacting holes in units of 2 e 2 /h. Our results are in agreement with reports using few-layer MoS 2 [8,10], trilayer WSe 2 [12] and monolayer MoS 2 [9], but the origin of the e 2 /h quantization remains unexplained. We attribute this broken valley and spin degeneracy to the formation of valley and spin polarised states of holes, which have been predicted for WS 2 [24,25] and in laterally gated MoS 2 quantum dots [26,27].…”

“…Realization of quantum devices based on two-dimensional (2D) materials has attracted significant interest in recent years [1,2]; in particular, advances in fabrication techniques for devices based on transition metal dichalcogenides (TMDs) enabled the realisation of building blocks of quantum circuits such as gate-controlled quantum dots in monolayer and few layer MoS 2 [3][4][5] and WSe 2 [6,7] as well as one-dimensional (1D) channels based on split gate technology [8][9][10][11][12]. 1D channels are of great interest in quantum information science because they have been established as valuable tools for non-invasive readout of semiconducting charge and spin qubits in GaAs [13], SiGe [14], graphene [15][16][17][18], bilayer graphene [19,20] and WSe 2 [21].…”

Gate‐Controlled Quantum Dots Based on 2D Materials

“…TMDs, such as MoS2, WS2, WSe2, and MoSe2, naturally have a band gap [200] of 1 to 2 eV, allowing demonstration of field-effect transistors (FETs) with a high on-off ratio [201] . QPCs based on TMDs have also been realized, in which the quantized conductance is observed and can be electrostatically pinched off [202][203][204][205] . Moreover, the coupled spin-valley degrees of freedom in TMDs provide possibilities for encoding information as well [73] .…”

“…[201] QPCs based on TMDs have also been realized, in which the quantized conductance is observed and can be electrostatically pinched off. [202][203][204][205] Moreover, the coupled spin-valley degrees of freedom in TMDs provide possibilities for encoding information as well. [73] Besides the common K valleys, which are similar to those studied in graphene, carriers from other valleys can also dominate the transport behavior in TMDs, due to the unique band structure and its layer-sensitive feature.…”

Charge detection using a WSe$_2$ van der Waals heterostructure

“…More recently, two-dimensional (2D) materials including graphene and semiconducting transition metal dichalcogenides (TMDs) emerged as a novel platform to realize electrostatically confined quantum circuits. Within the 2D materials platform, QPC's have been demonstrated in TMDs [5][6][7][8][9][10] , and more specifically, QPC charge detection has been demonstrated in monolayer and bilayer graphene (BLG) devices [11][12][13][14][15][16] . However, charge detection has not yet been implemented in semiconducting TMDs.…”