Gate-defined quantum point contact in an InAs two-dimensional electron gas

Abstract

We experimentally study quantized conductance in an electrostatically defined constriction in a high-mobility InAs two-dimensional electron gas. A parallel magnetic field lifts the spin degeneracy and allows for the observation of plateaus in integer multiples of e 2 /h. Upon the application of a perpendicular magnetic field, spin-resolved magnetoelectric subbands are visible. Through finite bias spectroscopy we measure the subband spacings in both parallel and perpendicular direction of the magnetic field and determine the g-factor.arXiv:1906.01995v2 [cond-mat.mes-hall]

Clean quantum point contacts in an InAs quantum well grown on a lattice-mismatched InP substrate

“…We report the investigation of quantized conductance and magnetotransport properties of a narrow gatedefined constriction, fabricated in a buried InAs 2DEG grown by molecular beam epitaxy (MBE) on an InP substrate. The 3.3% lattice mismatch 13 between InAs and InP leads to a compressive strain on the quantum well and introduces dislocation defects; we demonstrate that despite this, our QPCs are the cleanest amongst the handful of reported works in etched and gate-defined constrictions in InAs and InAs/InGaAs QWs [29][30][31][32][33] . The more closely lattice-matched substrate choice of GaSb has been plagued for decades with trivial edge conduction at mesa edges [34][35][36][37] which complicates interpretation of transport measurements.…”

Atomic‐Scale Characterization of Negative Differential Resistance in Ferroelectric Bi2WO6

“…In heterostructures with sufficiently confined layers, quantum interference effects begin to appear prominently in the motion of the electrons, and the carrier densities become quantum mechanically degenerate (e.g., quantum well). [39][40][41][42] Quantized energy levels of carriers in the quantum well lead to a significant change in the electron transport, [43,44] for example, resonant tunneling between the quantized surface states and the STM tip could result in intriguing NDR behaviors. [45] We performed electron transport simulations.…”

Universal conductance dips and fractional excitations in a two-subband quantum wire

“…It initiated extensive research activities on the quantum conductance, both in experiment and theory, which continue unabated. While the ballistic conductance is expected to be robust against interactions [3][4][5], deviations from the universal values are routinely observed [6][7][8][9][10][11][12][13][14][15][16][17][18][19], including mysterious conductance features that are unexpected from standard single-particle quantum mechanics, such as dips and new plateaus at fractional conductance values, strongly suggesting the importance of manybody interaction effects. Among these observations, the systems with a single transverse subband received most attention, targeting features such as uniform reduction of the conductance plateau [6,7,13,20,21], emergence of a small plateau around 0.7 × 2e 2 /h (also known as 0.7 anomaly) [8][9][10][11][12][22][23][24], re-entrant behavior [15,25], and signature of discrete resonant states [17].…”

“…Among these observations, the systems with a single transverse subband received most attention, targeting features such as uniform reduction of the conductance plateau [6,7,13,20,21], emergence of a small plateau around 0.7 × 2e 2 /h (also known as 0.7 anomaly) [8][9][10][11][12][22][23][24], re-entrant behavior [15,25], and signature of discrete resonant states [17]. More recent experiments on InAs, on the other hand, revealed exotic features also in the second plateau or above [14,16,19], which warrants theoretical investigation on the multi-subband regime. Since the III-V semiconductors, such as GaAs, InAs or InSb, host nuclei with nonzero spins, it motivates us to analyze a quantum wire based on a Kondo lattice model.…”