Strongly Correlated Fermi Systems

Abstract

Basing on the density functional theory of fermion condensation, we analyze the non-Fermi liquid behavior of strongly correlated Fermi-systems such as heavy-fermion metals. When deriving equations for the effective mass of quasiparticles, we consider solids with a lattice and homogeneous systems. We show that the low-temperature thermodynamic and transport properties are formed by quasiparticles, while the dependence of the effective mass on temperature, number density, magnetic fields, etc., gives rise to the non-Fermi liquid behavior. Our theoretical study of the heat capacity, magnetization, energy scales, the longitudinal magnetoresistance and magnetic entropy are in good agreement with the remarkable recent facts collected on the heavy-fermion metal YbRh 2 Si 2 .

Violation of the Time-Reversal and Particle-Hole Symmetries in Strongly Correlated Fermi Systems: A Review

“…The critical point of the corresponding phase transitions that we call ordinary phase transitions, can be shifted to absolute zero by varying the non-thermodynamic parameters such as chemical composition, P, B, etc. Both the ordered side of ordinary phase transition and disordered side are described within the framework of the LFL theory, supporting C and T symmetries [1,11,12,29]. As a result, one concludes that within the framework of ordinary quantum phase transition notion, it is impossible to explain the observed experimentally σ asym (V) and the corresponding C and T violations.…”

“…We note that such an asymmetry does not occur in conventional metals, especially at low temperatures. Since latter systems are well described by the Landau Fermi liquid (LFL) theory, which supports the particle-hole C symmetry, the differential tunneling conductivity and the dynamic conductance become symmetric functions of bias voltage V in them [1,[10][11][12].…”

“…HF compounds are fundamental systems in the condensed matter physics that are very well studied experimentally, which until very recently have lacked theoretical explanations [1,11,12]. Many notable and yet unexplained NFL properties of HTSC, HF metals and other strongly correlated fermionic systems are likely to be due to magnetic phase transitions of quantum nature [1,28].…”

“…One of the peculiar quantum phase transitions, taking place in the above systems, is so-called topological fermion condensation quantum phase transition (FCQPT). As a result of this transition, some of the fermions, comprising strongly correlated Fermi system, condense like bosons, see Refs [11][12][13] for details. These condensed fermions form fermion condensate (FC), which is responsible for many salient features, observed in the above systems.…”

“…These condensed fermions form fermion condensate (FC), which is responsible for many salient features, observed in the above systems. Among other things, the corresponding theoretical approach is able to describe the NFL properties of HTSC, HF metals, quantum spin liquids (for different number of spatial dimesions) as well as quasicrystals [1,[11][12][13][14][15]. The same approach, being applied to the differential tunneling conductivity in HF metals, shows convincingly, that latter quantity becomes significantly asymmetric function of bias voltage V. The underlying physical mechanism is the same as in the archetypical HF metal YbRh 2 Si 2 , where external parameters put the electronic subsystem near FCQPT point in the phase diagram.…”