constriction forming a quantum point contact. Zero-bias features in tunneling spectroscopy
appear at finite magnetic fields and oscillate in amplitude and split away from zero bias as a
function of magnetic field and gate voltage. A crossover in magnetoconductance is
observed: Magnetic fields above∼ 0.5 T enhance conductance in the low-conductance
(tunneling) regime but suppress conductance in the high-conductance (multichannel) …