Branch-Cut Singularities in Thermodynamics of Fermi Liquid Systems

The recently measured spin susceptibility of the two-dimensional electron gas exhibits a strong dependence on temperature, which is incompatible with the standard Fermi liquid phenomenology. In this article, we show that the observed temperature behavior is inherent to ballistic two-dimensional elec...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 2006-10, Vol.103 (43), p.15765-15769
Main Authors: Shekhter, Arkady, Finkel'stein, Alexander M.
Format: Article
Language:English
Subjects:
Analysis
Ballistics
Electron gas
Electrons
Fermi liquids
Gases
Low temperature
Magnetic polarity
Physical Sciences
Physics
Quasiparticles
Spin temperature
Temperature
Temperature dependence
Thermodynamics
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Summary:The recently measured spin susceptibility of the two-dimensional electron gas exhibits a strong dependence on temperature, which is incompatible with the standard Fermi liquid phenomenology. In this article, we show that the observed temperature behavior is inherent to ballistic two-dimensional electrons. Besides the singleparticle and collective excitations, the thermodynamics of Fermi liquid systems includes effects of the branch-cut singularities originating from the edges of the continuum of pairs of quasiparticles. As a result of the rescattering induced by interactions, the branch-cut singularities generate nonanalyticities in the thermodynamic potential that reveal themselves in anomalous temperature dependences. Calculation of the spin susceptibility in such a situation requires a nonperturbative treatment of the interactions. As in high-energy physics, a mixture of the collective excitations and pairs of quasiparticles can effectively be described by a pole in the complex momentum plane. This analysis provides a natural explanation for the observed temperature dependence of the spin susceptibility, both in sign and in magnitude.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.0607200103