Fractional Conductance Quantisation in MBE Grown High Mobility GaAs Quantum Wells.

Following the work of Thornton et al. [1] on split gate devices, the quantisation of conductance was discovered in electrostatically defined, narrow channels in quantum wells (quantum wires) [2,3]. In the low electron density and weak confinement regime, where the system is near to the transition to 2D, the energy levels are defined by electron interactions, rather than spatial confinement [4]. This regime of behaviour shows the existence of fractionally quantised conductance in the absence of a magnetic field. This was initially seen for holes in Ge and later for electrons in GaAs [5,6].



GaAs is particularly attractive due to the low disorder material which can be grown, providing exceptionally pure platforms on which to perform measurements. We report on fractional quantisation displayed in quantum wires grown on such materials and put them into the context of the theory set out by Shavit and Oreg, which suggests they arise due to coherent forward and backward scattering in a zig-zag array of electrons in the low electron density regimes [7].



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[5] - S. Kumar et al. 2019 Phys. Rev. Lett. 122, 086803

[6] - Kumar S and Pepper M 2021 Appl. Phys. Lett. 119, 110502

[7] - Shavit G and Oreg Y 2019 Phys. Rev. Lett. 123, 036803