Heyder, Jan and Bauer, Florian and Schubert, Enrico and Borowsky, David and Schuh, Dieter and Wegscheider, Werner and von Delft, Jan and Ludwig, Stefan (2015) Relation between the 0.7 anomaly and the Kondo effect: Geometric crossover between a quantum point contact and a Kondo quantum dot. PHYSICAL REVIEW B, 92 (19): 195401. ISSN 1098-0121, 1550-235X
Full text not available from this repository. (Request a copy)Abstract
Quantum point contacts (QPCs) and quantum dots (QDs), two elementary building blocks of semiconducting nanodevices, both exhibit famously anomalous conductance features: the 0.7 anomaly in the former case, the Kondo effect in the latter. For both the 0.7 anomaly and the Kondo effect, the conductance shows a remarkably similar low-energy dependence on temperature T, source-drain voltage V-sd and magnetic field B. In a recent publication [F. Bauer et al., Nature (London) 501, 73 (2013)], we argued that the reason for these similarities is that both a QPC and a Kondo QD (KQD) feature spin fluctuations that are induced by the sample geometry, confined in a small spatial regime, and enhanced by interactions. Here, we further explore this notion experimentally and theoretically by studying the geometric crossover between a QD and a QPC, focusing on the B-field dependence of the conductance. We introduce a one-dimensional model with local interactions that reproduces the essential features of the experiments, including a smooth transition between a KQD and a QPC with 0.7 anomaly. We find that in both cases the anomalously strong negative magnetoconductance goes hand in hand with strongly enhanced local spin fluctuations. Our experimental observations include, in addition to the Kondo effect in a QD and the 0.7 anomaly in a QPC, Fano interference effects in a regime of coexistence between QD and QPC physics, and Fabry-Perot-type resonances on the conductance plateaus of a clean QPC. We argue that Fabry-Perot-type resonances occur generically if the electrostatic potential of the QPC generates a flatter-than-parabolic barrier top.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | CARBON NANOTUBES; ELECTRON-GAS; LOCALIZATION; CONSTRICTION; PHYSICS; STATES; |
| Subjects: | 500 Science > 530 Physics |
| Divisions: | Physics > Institute of Experimental and Applied Physics > Chair Professor Huber > Group Rupert Huber |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 07 May 2019 11:39 |
| Last Modified: | 07 May 2019 11:39 |
| URI: | https://pred.uni-regensburg.de/id/eprint/4478 |
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