Abstract
Oxide heterostructures are versatile platforms with which to research and create novel functional nanostructures. We successfully develop one-dimensional (1D) quantum-wire devices using quantum point contacts on MgZnO/ZnO heterostructures and observe ballistic electron transport with conductance quantised in units of 2e^{2}/h. Using DC-bias and in-plane field measurements, we find that the g-factor is enhanced to around 6.8, more than three times the value in bulk ZnO. We show that the effective mass m^{*} increases as the electron density decreases, resulting from the strong electron-electron interactions. In this strongly interacting 1D system we study features matching the 0.7 conductance anomalies up to the fifth subband. This paper demonstrates that high-mobility oxide heterostructures such as this can provide good alternatives to conventional III-V semiconductors in spintronics and quantum computing as they do not have their unavoidable dephasing from nuclear spins. This paves a way for the development of qubits benefiting from the low defects of an undoped heterostructure together with the long spin lifetimes achievable in silicon.
Highlights
Physical phenomena in transition-metal oxides and their complex compounds have stimulated intense interest in research covering metallic, semiconducting, and insulating properties
We successfully develop one-dimensional (1D) quantum-wire devices using quantum point contacts on MgZnO/ZnO heterostructures and observe ballistic electron transport with conductance quantised in units of 2e2/h
This paper demonstrates that high-mobility oxide heterostructures such as this can provide good alternatives to conventional III-V semiconductors in spintronics and quantum computing as they do not have their unavoidable dephasing from nuclear spins
Summary
Physical phenomena in transition-metal oxides and their complex compounds have stimulated intense interest in research covering metallic, semiconducting, and insulating properties. The lateral electrostatic confinement creates a series of 1D subbands, in which spin-up (↑) and spin-down (↓) subbands each contribute e2/h This is already observed in many materials, including GaAs/AlGaAs,[13,14] InGaAs/InAlAs,[15] GaN/AlGaN heterostructures,[16] strained epitaxial germanium[17] and carbon-based materials.[18,19] An anomalous feature at conductance G = 0.7 × 2e2/h was first investigated by Thomas et al and attributed to a possible spontaneous spin polarisation.[20,21] Its origin has since been much debated,[22] and other explanations proposed including quasi-bound-state formation and the Kondo effect.[23,24] Recently, Bauer et al used a smeared van Hove singularity to explain it and emphasised the important role that electron-electron interactions play in the 0.7 anomaly.[25]. -2.5 measurement of the strength of the electron-electron interaction from the electron effective mass.[25]
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