in the vicinity of the Fermi surface. We demonstrate that the quasiparticle subsystem responsible for the flat spectrum possesses the same thermodynamic properties as a gas of localized spins. Theoretical results compare favorably with available experimental data. While departing radically from prevalent views on the origin of non-Fermi-liquid behavior, the theory advanced here is nevertheless a conservative one of in continuing to operate within the general framework of Landau theory.

DOI: 10.1142/9789812709592_0004

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Thermodynamic properties of Fermi systems with flat single-particle spectra

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TOPOLOGICAL PHASE TRANSITIONS IN STRONGLY CORRELATED FERMI SYSTEMS

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Is there a unified theory explaining all correlated electron systems?

Tao Li

The Landau theory of phase and phase transition, which describes the state of matter by the spontaneous symmetry breaking, and the Fermi liquid theory of interacting Fermi systems are the two corner stones of contemporary condensed matter physics. They act as our starting points to understand the structure, excitations and phase transitions of any condensed matter system. According to such a Landau paradigm, an interacting Fermi system will behave just as non-interacting Fermi gas system at sufficient low energy, if the interaction is not strong enough to induce a symmetry breaking phase transition in the system. In such a case, the perturbation expansion in the interaction strength is assumed to converge and the low energy excitation can be connected to that of a Fermi gas system adiabatically. In strongly correlated electron systems, such as the high temperature superconductors and quantum antiferromagnets, a pertubative picture on the interaction effect usually fails. 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Such an extension will elevate our understanding of the structure of matter to the level of quantum wave function. Unlike the conventional symmetry breaking order, which is characterized by the correlation functions between local physical observables, the new form of orders, which are commonly called quantum order (with the topological order as one of its typical example), can be better characterized by the entanglement property in the quantum wave function. From a mathematical point of view, the new form of order is closely related to the projective representation theory of the symmetry group, while the conventional symmetry breaking order is well described by the linear representation theory of the symmetry group.The Landau theory of phase and phase transition, which describes the state of matter by the spontaneous symmetry breaking, and the Fermi liquid theory of interacting Fermi systems are the two corner stones of contemporary condensed matter physics. 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Unlike the conventional symmetry breaking order, which is characterized by the correlation functions between local physical observables, the new form of orders, which are commonly called quantum order (with the topological order as one of its typical example), can be better characterized by the entanglement property in the quantum wave function. From a mathematical point of view, the new form of order is closely related to the projective representation theory of the symmetry group, while the conventional symmetry breaking order is well described by the linear representation theory of the symmetry group.

Chinese Science Bulletin (Chinese Version)Nov 8, 20161 citation

The interplay between flattening and damping of single particle spectra in strongly correlated Fermi systems

VICTOR A. KHODEL, MIKHAIL V. ZVEREV

The self-consistent theory of the fermion condensation, a specific phase transition which results in a rearrangement of the single particle degrees of freedom in strongly correlated Fermi systems is developed. Beyond the phase transition point, the single particle spectra are shown to be flat. The interplay between the flattening and the damping of the single particle spectra at $T\to 0$ is investigated. The width $γ(ε)$ of the single particle states is found to grow up linearly with $ε$ over a wide range of energy as in a marginal Fermi liquid. Our results gain insight into the success of the phenomenological theory of the normal states of high-temperature superconductors by Varma et al.The self-consistent theory of the fermion condensation, a specific phase transition which results in a rearrangement of the single particle degrees of freedom in strongly correlated Fermi systems is developed. Beyond the phase transition point, the single particle spectra are shown to be flat. The interplay between the flattening and the damping of the single particle spectra at $T\to 0$ is investigated. The width $γ(ε)$ of the single particle states is found to grow up linearly with $ε$ over a wide range of energy as in a marginal Fermi liquid. Our results gain insight into the success of the phenomenological theory of the normal states of high-temperature superconductors by Varma et al.

arXiv:cond-mat/9907061Jul 5, 19990 citations

ε({\bf p})

T\to 0

is investigated. The width

γ(ε)

of the single particle states is found to grow up linearly with

ε

over a wide range of energy as in a marginal Fermi liquid. Our results gain insight into the success of the phenomenological theory of the normal states of high-temperature superconductors by Varma et al.