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Spin Fluctuations in the 0.7 Anomaly in Quantum Point Contacts
Dennis H Schimmel1, Benedikt Bruognolo1,2, Jan von Delft1
1Physics Department, Arnold Sommerfeld Center for Theoretical Physics, and Center for NanoScience, Ludwig-Maximilians-Universität, Theresienstraße 37, 80333 Munich, Germany.
Physical Review Letters
|December 9, 2017
Summary
Interactions in quantum point contacts (QPCs) explain the 0.7 anomaly by enhancing the van Hove ridge. This leads to temperature-dependent conductance and longer traversal times due to fluctuating spin structures.
Area of Science:
- Condensed matter physics
- Quantum electronics
Background:
- The 0.7 anomaly in quantum point contacts (QPCs) is a puzzling phenomenon.
- Previous theories suggest an enhanced density of states at the van Hove ridge influences interactions.
Purpose of the Study:
- To investigate the impact of interactions on dynamical quantities in QPCs.
- To understand the role of the van Hove ridge in the 0.7 anomaly.
Main Methods:
- Analysis of interaction effects on dynamical properties.
- Theoretical modeling of quantum point contact behavior.
Main Results:
- Interactions pin the van Hove ridge to the chemical potential in sub-open QPCs.
- A temperature dependence of linear conductance is observed, consistent with experimental data.
- Dynamical spin susceptibility is significantly enhanced.
- QPC traversal time is notably lengthened.
Conclusions:
- Electrons traverse QPCs through slowly fluctuating, spatially extended spin structures.
- The enhanced van Hove ridge and resulting interactions are crucial for understanding QPC anomalies.
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