Weak magnetism and non-Fermi liquids near heavy-fermion critical points (original) (raw)
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Origin of non-Fermi liquid behavior in heavy fermion systems: A conceptual view
We critically examine the non-Fermi liquid (NFL) behavior observed in heavy fermion systems located close to a magnetic instability and suggest a conceptual advance in physics in order to explain its origin. We argue that the treatment of electronic states responsible for magnetism near the Quantum Critical Point (QCP), should not be accomplished within the quantum mechanical formalism; instead they should be treated semi-classically. The observed NFL behavior can be explained within such a scenario. As a sequel we attempt to discuss its consequences for the explanation of high-TC superconductivity observed in Cuprates.
Theories of non-Fermi liquid behavior in heavy fermions
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I will review our incomplete understanding of non-Fermi liquid behavior in heavy fermion systems at a quantum critical point. General considerations suggest that critical antiferromagnetic fluctuations do not destroy the Fermi surface by scattering the heavy electrons-but by actually breaking up the internal structure of the heavy fermion. I contrast the weak, and strong-coupling view of the quantum phase transition, emphasizing puzzles and questions that recent experiments raise.
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Nature, 2008
For the past half century, our understanding of how the interactions between electrons affect the low-temperature properties of metals has been based on the Landau theory of a Fermi liquid 1 . In recent times, however, there have been an increasingly large number of examples in which the predictions of the Fermi-liquid theory appear to be violated 2 . Although the qualitative reasons for the breakdown are generally understood, the specific quantum states that replace the Fermi liquid remain in many cases unclear. Here we describe an example of such a breakdown where the non-Fermi-liquid properties can be interpreted. We show that the thermal and electrical resistivities in high-purity samples of the d-electron metal ZrZn 2 at low temperatures have T and T 5/3 temperature dependences, respectively: these are the signatures of the 'marginal' Fermi-liquid state 3-7 , expected to arise from effective long-range spin-spin interactions in a metal on the border of metallic ferromagnetism in three dimensions 3,5 . The marginal Fermi liquid provides a link between the conventional Fermi liquid and more exotic non-Fermi-liquid states that are of growing interest in condensed matter physics. The idea of a marginal Fermi liquid has also arisen in other contextsfor example, in the phenomenology of the normal state of the copper oxide superconductors 7 , and in studies of relativistic plasmas and of nuclear matter 3,4,6 .
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Journal of Experimental and Theoretical Physics Letters, 2002
We show that a strongly correlated Fermi system with the fermion condensate, which exhibits strong deviations from Landau Fermi liquid behavior, is driven into the Landau Fermi liquid by applying a small magnetic field B at temperature T = 0. This field-induced Landau Fermi liquid behavior provides the constancy of the Kadowaki-Woods ratio. A re-entrance into the strongly correlated regime is observed if the magnetic field B decreases to zero, then the effective mass M * diverges as M * ∝ 1/ √ B. At finite temperatures, the strongly correlated regime is restored at some temperature T * ∝ √ B. This behavior is of general form and takes place in both three dimensional and two dimensional strongly correlated systems. We demonstrate that the observed 1/ √ B divergence of the effective mass and other specific features of heavy-fermion metals are accounted for by our consideration.
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Journal of Physics: Condensed Matter, 1996
The Fermionic Chern-Simons approach has had remarkable success in the description of quantum Hall states at even denominator filling fractions ν = 1 2m. In this paper we review a number of recent works concerned with modeling this state as a Landau-Silin Fermi liquid. We will then focus on one particular problem with constructing such a Landau theory that becomes apparent in the limit of high magnetic field, or equivalently the limit of small electron band mass m b. In this limit, the static response of electrons to a spatially varying magnetic field is largely determined by kinetic energy considerations. We then remedy this problem by attaching an orbital magnetization to each fermion to separate the current into magnetization and transport contributions, associated with the cyclotron and guiding center motions respectively. This leads us to a description of the ν = 1 2m state as a Fermi liquid of magnetized composite fermions which correctly predicts the m b dependence of the static and dynamic response in the limit m b → 0. As an aside, we derive a sum rule for the Fermi liquid coefficients for the Chern-Simons Fermi liquid. This paper is intended to be readable by people who may not be completely familiar with this field.
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