Quantum critical behavior of heavy fermions: Quasiparticles in the Gaussian fluctuation regime
✍ Scribed by P. Wölfle; E. Abrahams
- Publisher
- John Wiley and Sons
- Year
- 2011
- Tongue
- English
- Weight
- 262 KB
- Volume
- 523
- Category
- Article
- ISSN
- 0003-3804
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✦ Synopsis
Abstract
Landau quasiparticle (qp) theory may be extended into the non‐Fermi liquid regime of metallic compounds near a quantum critical point (QCP), provided the width of the quasiparticle states is less than their energy. Sufficiently far from the QCP, when the critical fluctuations are non‐interacting, their influence on the qp properties may be calculated in a controlled way. A prominent example is the `marginal Fermi liquid,' characterized by a logarithmic variation of the specific heat coefficient and a linear variation of the resistivity with temperature. The latter is induced by the interaction of qps with three‐dimensional ferromagnetic (FM) or, in a disordered system, with quasi‐two‐dimensional antiferromagnetic (AFM) spin fluctuations. It is argued that both types of fluctuations are present in YbRh~2~Si~2~. It is suggested that the experimentally observed crossover line at T* marks the changeover from AFM to FM fluctuations with increasing magnetic field. The non‐Fermi liquid behavior found in the electron spin resonance data on YbRh~2~Si~2~ may be completely interpreted using critical quasiparticle theory.