Signatures of exchange correlations in the thermopower of quantum dots

Gabriel Billings, A. Douglas Stone, and Y. Alhassid
Phys. Rev. B 81, 205303 – Published 4 May 2010

Abstract

We use a many-body rate-equation approach to calculate the thermopower of a quantum dot in the presence of an exchange interaction. At temperatures much smaller than the single-particle level spacing, the known quantum jumps (discontinuities) in the thermopower are split by the exchange interaction. The origin and nature of the splitting are elucidated with a simple physical argument based on the nature of the intermediate excited state in the sequential tunneling approach. We show that this splitting is sensitive to the number parity of electrons in the dot and the dot’s ground-state spin. These effects are suppressed when cotunneling dominates the electrical and thermal conductances. We calculate the thermopower in the presence of elastic cotunneling and show that some signatures of exchange correlations should still be observed with current experimental methods. In particular, we propose a method to determine the strength of the exchange interaction from measurements of the thermopower.

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  • Received 17 February 2010

DOI:https://doi.org/10.1103/PhysRevB.81.205303

©2010 American Physical Society

Authors & Affiliations

Gabriel Billings

  • Department of Physics, Stanford University, Stanford, California 94305, USA

A. Douglas Stone

  • Department of Applied Physics, Yale University, Post Office Box 208284, New Haven, Connecticut 06520, USA

Y. Alhassid

  • Center for Theoretical Physics, Sloane Physics Laboratory, Yale University, New Haven, Connecticut 06520, USA

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Vol. 81, Iss. 20 — 15 May 2010

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