Magnetic field effects in few-level quantum dots: theory, and application to experiment

Journal article

We examine several effects of an applied magnetic field on Anderson-type models for both single- and two-level quantum dots, and make direct comparison between numerical renormalization group (NRG) calculations and recent conductance measurements. On the theoretical side the focus is on magnetization, single-particle dynamics and zero-bias conductance, with emphasis on the universality arising in strongly correlated regimes; including a method to obtain the scaling behavior of field-induced Kondo resonance shifts over a very wide field range. NRG is also used to interpret recent experiments on spin-1/2 and spin-1 quantum dots in a magnetic field, which we argue do not wholly probe universal regimes of behavior; and the calculations are shown to yield good qualitative agreement with essentially all features seen in experiment. The results capture in particular the observed field-dependence of the Kondo conductance peak in a spin-1/2 dot, with quantitative deviations from experiment occurring at fields in excess of $\sim$ 5 T, indicating the eventual inadequacy of using the equilibrium single-particle spectrum to calculate the conductance at finite bias.

Authors: Wright, C; Galpin, MR; Logan, D

• Publication status: Published
• Journal: Phys. Rev. B
• Volume: 84
• Issue: 11
• Pages: 115308
• Publication date: 2011-07-13
• DOI: 10.1103/PhysRevB.84.115308
• EISSN: 1550-235X
• ISSN: 1098-0121
• Language: English
• Keywords: cond-mat.mes-hall; cond-mat.str-el