Nuclear magnetic resonance probes for the Kondo scenario for the 0.7 feature in semiconductor quantum point contact devices

Abstract

We propose a probe based on nuclear relaxation and Knight shift measurements for the Kondo scenario for the "0.7 feature" in semiconductor quantum point contact (QPC) devices. We show that the presence of a bound electron in the QPC would lead to a much higher rate of nuclear relaxation compared to nuclear relaxation through exchange of spin with conduction electrons. Furthermore, we show that the temperature dependence of this nuclear relaxation is very non-monotonic as opposed to the linear-T relaxation from coupling with conduction electrons. We present a qualitative analysis for the additional relaxation due to nuclear spin diffusion (NSD) and study the extent to which NSD affects the range of validity of our method. The conclusion is that nuclear relaxation, in combination with Knight shift measurements, can be used to verify whether the 0.7 feature is indeed due to the presence of a bound electron in the QPC.

Published version. Appears in a Special Section on the 0.7 Feature and Interactions in One-Dimensional Systems. 16 pages

References in corpus (7)

• Magnetic impurity formation in quantum point contacts
• Dynamics of Quantum Dot Nuclear Spin Polarization Controlled by a Single Electron
• Energy-level pinning and the 0.7 spin state in one dimension: GaAs quantum wires studied using finite-bias spectroscopy
• Anomalous spin-dependent behaviour of one-dimensional subbands
• Suppression of Shot Noise in Quantum Point Contacts in the "0.7" Regime
• Quantum point contact with large localized spin: fractional quantization of the ballistic conductance
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Cited by in corpus (3)

• Spin-Polarized STM for a Kondo adatom
• Theory of NMR in semiconductor quantum point contact devices
• Kondo Lattice Scenario in Disordered Semiconductor Heterostructures