title: On the zero-bias anomaly and Kondo physics in quantum point contacts near pinch-off.
abstract: We investigate the linear and non-linear conductance of quantum point contacts (QPCs), in the region near pinch-off where Kondo physics has previously been connected to the appearance of the 0.7 feature. In studies of seven different QPCs, fabricated in the same high-mobility GaAs/AlGaAs heterojunction, the linear conductance is widely found to show the presence of the 0.7 feature. The differential conductance, on the other hand, does not generally exhibit the zero-bias anomaly (ZBA) that has been proposed to indicate the Kondo effect. Indeed, even in the small subset of QPCs found to exhibit such an anomaly, the linear conductance does not always follow the universal temperature-dependent scaling behavior expected for the Kondo effect. Taken collectively, our observations demonstrate that, unlike the 0.7 feature, the ZBA is not a generic feature of low-temperature QPC conduction. We furthermore conclude that the mere observation of the ZBA alone is insufficient evidence for concluding that Kondo physics is active. While we do not rule out the possibility that the Kondo effect may occur in QPCs, our results appear to indicate that its observation requires a very strict set of conditions to be satisfied. This should be contrasted with the case of the 0.7 feature, which has been apparent since the earliest experimental investigations of QPC transport.
authors.affiliation: Graduate School of Advanced Integration Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Xiang
authors.forename: S
authors.initials: S
authors.lastname: Xiao
authors.forename: K
authors.initials: K
authors.lastname: Fuji
authors.forename: K
authors.initials: K
authors.lastname: Shibuya
authors.forename: T
authors.initials: T
authors.lastname: Endo
authors.forename: N
authors.initials: N
authors.lastname: Yumoto
authors.forename: T
authors.initials: T
authors.lastname: Morimoto
authors.forename: N
authors.initials: N
authors.lastname: Aoki
authors.forename: J P
authors.initials: JP
authors.lastname: Bird
authors.forename: Y
authors.initials: Y
authors.lastname: Ochiai
mesh_terms: D017607:Aluminum Compounds / Q000737:chemistry*; D001152:Arsenicals / Q000737:chemistry*; D003198:Computer Simulation; D004553:Electric Conductivity; D004566:Electrodes; D004574:Electromagnetic Fields; D005708:Gallium / Q000737:chemistry*; D008956:Models, Chemical; D011789:Quantum Theory; D012666:Semiconductors
chemical_list: D017607:Aluminum Compounds; D001152:Arsenicals; C043055:gallium arsenide; D005708:Gallium