Showing papers on "Fermi liquid theory published in 2004"
TL;DR: The intrinsic anomalous Hall effect in metallic ferromagnets is shown to be controlled by Berry phases accumulated by adiabatic motion of quasiparticles on the Fermi surface, and is purely a Ferm i-liquid property, not a bulk FermI sea property like Landau diamagnetism.
Abstract: The intrinsic anomalous Hall effect in metallic ferromagnets is shown to be controlled by Berry phases accumulated by adiabatic motion of quasiparticles on the Fermi surface, and is purely a Fermi-liquid property, not a bulk Fermi sea property like Landau diamagnetism, as has been previously supposed. Berry phases are a new topological ingredient that must be added to Landau Fermi-liquid theory in the presence of broken inversion or time-reversal symmetry.
533 citations
TL;DR: In this article, the authors explore the hypothesis that the primary fluctuations responsible for the non-Fermi liquid physics are those associated with the destruction of the large Fermi surface of the Fermani liquid.
Abstract: This paper is concerned with the weak-moment magnetism in heavy-fermion materials and its relation to the non-Fermi liquid physics observed near the transition to the Fermi liquid. We explore the hypothesis that the primary fluctuations responsible for the non-Fermi liquid physics are those associated with the destruction of the large Fermi surface of the Fermi liquid. Magnetism is suggested to be a low-energy instability of the resulting small Fermi surface state. A concrete realization of this picture is provided by a fractionalized Fermi liquid state which has a small Fermi surface of conduction electrons, but also has other exotic excitations with interactions described by a gauge theory in its deconfined phase. Of particular interest is a three-dimensional fractionalized Fermi liquid with a spinon Fermi surface and a U(1) gauge structure. A direct second-order transition from this state to the conventional Fermi liquid is possible and involves a jump in the electron Fermi surface volume. The critical point displays non-Fermi liquid behavior. A magnetic phase may develop from a spin density wave instability of the spinon Fermi surface. This exotic magnetic metal may have a weak ordered moment although the local moments do not participate in the Fermi surface. Experimental signatures of this phase and implications for heavy-fermion systems are discussed.
473 citations
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01 Jan 2004
TL;DR: In this paper, the first and second quantization of the electron gas and the phonons were performed, and a Fourier transformation was performed on the resulting Fourier Transform was applied to the Luttinger liquid.
Abstract: 1. First and second quantization 2. The electron gas 3. Phonons: coupling to electrons 4. Mean field theory 5. Time evolution pictures 6. Linear response theory 7. Transport in mesoscopic systems 8. Green's functions 9. Equation of motion theory 10. Transport in interacting mesoscopic systems 11. Imaginary time Green's functions 12. Feynman diagrams and external potentials 13. Feynman diagrams and pair interactions 14. The interacting electron gas 15. Fermi liquid theory 16. Impurity scattering and conductivity 17. Green's functions and phonons 18. Superconductivity 19. 1D electron gases and Luttinger liquids A. Fourier transformations B. Exercises C. Index
304 citations
TL;DR: In this article, it has been suggested that non-Fermi-liquid phases of metals may exist in some heavy-fermion compounds and oxide materials, but the discovery of a characteristic microscopic signature of such phases presents a major challenge.
Abstract: Only a few metallic phases have been identified in pure crystalline materials. These include normal, ferromagnetic and antiferromagnetic metals, systems with spin and charge density wave order, and superconductors. Fermi-liquid theory provides a basis for the description of all of these phases. It has been suggested that non-Fermi-liquid phases of metals may exist in some heavy-fermion compounds and oxide materials, but the discovery of a characteristic microscopic signature of such phases presents a major challenge. The transition-metal compound MnSi above a certain pressure (p(c) = 14.6 kbar) provides what may be the cleanest example of an extended non-Fermi-liquid phase in a three-dimensional metal. The bulk properties of MnSi suggest that long-range magnetic order is suppressed at p(c) (refs 7-12). Here we report neutron diffraction measurements of MnSi, revealing that sizeable quasi-static magnetic moments survive far into the non-Fermi-liquid phase. These moments are organized in an unusual pattern with partial long-range order. Our observation supports the existence of novel metallic phases with partial ordering of the conduction electrons (reminiscent of liquid crystals), as proposed for the high-temperature superconductors and heavy-fermion compounds.
295 citations
TL;DR: Experimental evidence is presented for the formation of a nonsuperconducting phase in the vicinity of a magnetic field–tuned quantum critical point in ultrapure crystals of the ruthenate metal Sr3Ru2O7, and the possibility that the observed phase is due to a spin-dependent symmetry-breaking Fermi surface distortion is discussed.
Abstract: Condensed systems of strongly interacting electrons are ideal for the study of quantum complexity. It has become possible to promote the formation of new quantum phases by explicitly tuning systems toward special low-temperature quantum critical points. So far, the clearest examples have been appearances of superconductivity near pressure-tuned antiferromagnetic quantum critical points. We present experimental evidence for the formation of a nonsuperconducting phase in the vicinity of a magnetic field-tuned quantum critical point in ultrapure crystals of the ruthenate metal Sr3Ru2O7, and we discuss the possibility that the observed phase is due to a spin-dependent symmetry-breaking Fermi surface distortion.
198 citations
TL;DR: The phase diagram at low temperatures, and in the limit of strong atom-atom interactions, is discussed, and the existence of quantum phases that involve pairing of fermions with one or more bosons, or, respectively, bosonic holes are predicted.
Abstract: A mixture of ultracold bosons and fermions placed in an optical lattice constitutes a novel kind of quantum gas, and leads to phenomena, which so far has been discussed neither in atomic physics, nor in condensed matter physics. We discuss the phase diagram at low temperatures, and in the limit of strong atom-atom interactions, and predict the existence of quantum phases that involve pairing of fermions with one or more bosons, or, respectively, bosonic holes. The resulting composite fermions may form, depending on the system parameters, a normal Fermi liquid, a density wave, a superfluid liquid, or an insulator with fermionic domains. We discuss the feasibility for observing such phases in current experiments.
191 citations
TL;DR: It is shown that self-energy and excitonic effects in single wall carbon nanotubes can be understood in a theory of large radius tubes derived from the theory of two dimensional graphene where the Coulomb interaction leads to a logarithmic correction to the electronic self- energy and marginal Fermi liquid behavior.
Abstract: Recent fluorescence spectroscopy experiments on single wall carbon nanotubes reveal substantial deviations of observed absorption and emission energies from predictions of noninteracting models of the electronic structure. Nonetheless, the data for nearly armchair nanotubes obey a nonlinear scaling relation as a function of the tube radius R. We show that these effects can be understood in a theory of large radius tubes, derived from the theory of two dimensional graphene where the Coulomb interaction leads to a logarithmic correction to the electronic self-energy and marginal Fermi liquid behavior. Interactions on length scales larger than the tube circumference lead to strong self-energy and excitonic effects that compete and nearly cancel so that the observed optical transitions are dominated by the graphene self-energy effects.
167 citations
TL;DR: In this paper, it was shown that there must always exist intermediate microemulsion phases, and an accompanying sequence of continuous phase transitions, including stripe-related analogues of classical smectics and nematics.
Abstract: We show that there can be no direct first-order transition between a Fermi liquid and an insulating electronic (Wigner) crystalline phase in a clean two-dimensional electron gas in a metal-oxide-semiconductor field-effect transistor (MOSFET); rather, there must always exist intermediate ``microemulsion'' phases, and an accompanying sequence of continuous phase transitions. Among the intermediate phases which we find are a variety of electronic liquid crystalline phases, including stripe-related analogues of classical smectics and nematics. The existence of these phases can be established in the neighborhood of the phase boundaries on the basis of an asymptotically exact analysis, and reasonable estimates can be made concerning the ranges of electron densities and device geometries in which they exist. They likely occur in clean Si MOSFETs in the range of densities in which an ``apparent metal to insulator transition'' has been observed in existing experiments. We also point out that, in analogy with the Pomaranchuk effect in $^{3}\mathrm{He}$, the Wigner crystalline phase has higher spin entropy than the liquid phase, leading to an increasing tendency to crystallization with increasing temperature.
149 citations
TL;DR: This report reports on the first direct observation of a transition from a Tomonaga-Luttinger liquid to a Fermi-liquid behavior in potassium-intercalated mats of single-wall carbon nanotubes.
Abstract: We report on the first direct observation of a transition from a Tomonaga-Luttinger liquid to a Fermi-liquid behavior in potassium-intercalated mats of single-wall carbon nanotubes. Using high resolution photoemission spectroscopy, an analysis of the spectral shape near the Fermi level reveals a Tomonaga-Luttinger liquid power law scaling in the density of states for the pristine sample and for low dopant concentration. As soon as the doping is high enough to achieve a filling of the conduction bands of the semiconducting tubes, a distinct transition to metallic single-wall carbon nanotube bundles with the scaling behavior of a normal Fermi liquid occurs.
121 citations
TL;DR: Verification of the Wiedemann-Franz law, kappa/T=L(0)/rho as T-->0, and observation of a T2 dependence of rho at low temperature establish the existence of a well-defined Fermi-liquid state.
Abstract: The in-plane resistivity rho and thermal conductivity kappa of single crystal Na0.7CoO2 were measured down to 40 mK. Verification of the Wiedemann-Franz law, kappa/T=L(0)/rho as T-->0, and observation of a T2 dependence of rho at low temperature establish the existence of a well-defined Fermi-liquid state. The measured value of coefficient A reveals enormous electron-electron scattering, characterized by the largest Kadowaki-Woods ratio A/gamma(2) encountered in any material. The rapid suppression of A with magnetic field suggests a possible proximity to a magnetic quantum critical point. We also speculate on the possible role of magnetic frustration and proximity to a Mott insulator.
107 citations
TL;DR: In this paper, anisotropic resistivity and heat capacity measurements down to 0.4 K and up to 140 kOe are reported for a single crystalline YbAgGe, a member of the hexagonal RAgGe serie.
Abstract: Detailed anisotropic resistivity and heat-capacity measurements down to $\ensuremath{\sim}0.4\mathrm{K}$ and up to 140 kOe are reported for a single crystalline YbAgGe. Based on these data YbAgGe, a member of the hexagonal RAgGe serie, can be classified as new, stoichiometric heavy-fermion compound with two magnetic ordering temperatures below 1 K and field-induced non-Fermi-liquid behavior above 45--70 kOe and 80--110 kOe for $H\ensuremath{\Vert}\mathrm{ab}$ and $H\ensuremath{\Vert}c,$ respectively.
TL;DR: In this paper, the authors show that most nuclear phenomena can be reproduced by theories using either density-independent, or density-dependent masses, a grand conspiracy of nature that is an aspect that could be tied to the Cheshire Cat phenomenon in hadron physics.
TL;DR: Oshikawa et al. as mentioned in this paper extended Luttinger's theorem to exotic systems which exhibit quantum number fractionalization focusing on fractionalized insulators, superfluids and Fermi liquids.
Abstract: Luttinger's theorem for Fermi liquids equates the volume enclosed by the Fermi surface in momentum space to the electron filling, independent of the strength and nature of interactions. Motivated by recent momentum balance arguments that establish this result in a nonperturbative fashion [M. Oshikawa, Phys. Rev. Lett. 84, 3370 (2000)], we present extensions of this momentum balance argument to exotic systems which exhibit quantum number fractionalization focusing on ${Z}_{2}$ fractionalized insulators, superfluids and Fermi liquids. These lead to nontrivial relations between the particle filling and some intrinsic property of these quantum phases, and hence may be regarded as natural extensions of Luttinger's theorem. We find that there is an important distinction between fractionalized states arising naturally from half filling versus those arising from integer filling. We also note how these results can be useful for identifying fractionalized states in numerical experiments.
TL;DR: In this paper, the authors used the dynamical mean field method to investigate electronic properties of heterostructures in which finite number of Mott insulator layers are embedded in a spatially infinite band-insulator.
Abstract: We use the dynamical mean field method to investigate electronic properties of heterostructures in which finite number of Mott-insulator layers are embedded in a spatially infinite band-insulator. The evolution of the correlation effects with the number of Mott insulating layers and with position in the heterostructure is determined, and the optical conductivity is computed. It is shown that the heterostructures are generally metallic, with moderately renormalized bands of quasiparticles appearing at the interface between the correlated and uncorrelated regions.
TL;DR: This work proposes a new mechanism in which spin-orbit coupling can be generated dynamically in strongly correlated, nonrelativistic systems as the result of Fermi surface instabilities in higher angular momentum channels.
Abstract: Spin-orbit coupling plays an important role in determining the properties of solids, and is crucial for spintronics device applications. Conventional spin-orbit coupling arises microscopically from relativistic effects described by the Dirac equation, and is described as a single particle band effect. In this work, we propose a new mechanism in which spin-orbit coupling can be generated dynamically in strongly correlated, nonrelativistic systems as the result of Fermi surface instabilities in higher angular momentum channels. Various spin-orbit couplings can emerge in these new phases, and their magnitudes can be continuously tuned by temperature or other quantum parameters.
TL;DR: In this article, the effect of Coulomb repulsion on the electronic properties of Na0.7CoO2 has been investigated, showing that the anomalous thermopower and Hall effect may be interpreted along these lines.
Abstract: Charge frustration due to further neighbor Coulomb repulsion can have dramatic effects on the electronic properties of NaxCoO2 in the full doping range. It can significantly reduce the effective mobility of the charge carriers, leading to a low degeneracy temperature epsilonF<~T. Such strongly renormalized Fermi liquid has rather unusual properties—from the point of view of the ordinary metals with epsilonFT—but similar to the properties that are actually observed in the NaxCoO2 system. For example, we show that the anomalous thermopower and Hall effect observed in Na0.7CoO2 may be interpreted along these lines. If the repulsion is strong, it can also lead to charge order; nevertheless, away from the commensurate dopings, the configurational constraints allow some mobility for the charge carriers, i.e., there remains some "metallic" component. Finally, the particularly strong bandwidth suppression around the commensurate x = 1/3 can help resurrect the resonating valence bond superconductivity, which would otherwise not be expected near this high doping. These suggestions are demonstrated specifically for a tJ-like model with an additional nearest-neighbor repulsion.
TL;DR: In this article, the formation of an electronic nematic phase characterized by a broken point-group symmetry in interacting fermion systems within the weak coupling theory was studied, and the origin of the first-order transition and competition with other broken symmetry states was discussed.
Abstract: We study the formation of an electronic nematic phase characterized by a broken point-group symmetry in interacting fermion systems within the weak coupling theory. As a function of interaction strength and chemical potential, the phase transition between the isotropic Fermi liquid and nematic phase is first order at zero temperature and becomes second order at a finite temperature. The transition is present for all typical, including quasi-two-dimensional, electronic dispersions on the square lattice and takes place for arbitrarily small interaction when at van Hove filling, thus suppressing the Lifshitz transition. In connection with the formation of the nematic phase, we discuss the origin of the first-order transition and competition with other broken symmetry states.
TL;DR: In this paper, it was shown that the temperature zero renormalized perturbation expansions of a class of interacting many-fermion models in two space dimensions have nonzero radius of convergence.
Abstract: In a series of ten papers (see the flow chart at the end of §I), of which this is the first, we prove that the temperature zero renormalized perturbation expansions of a class of interacting many–fermion models in two space dimensions have nonzero radius of convergence. The models have ‘‘asymmetric’’ Fermi surfaces and short range interactions. One consequence of the convergence of the perturbation expansions is the existence of a discontinuity in the particle number density at the Fermi surface. Here, we present a self contained formulation of our main results and give an overview of the methods used to prove them.
TL;DR: In this article, the generalized Kadowaki-Woods relation in the strong coupling limit was studied in the orbitally degenerate periodic Anderson model, and it was shown that A γ -2 is the lower bound of the K-woods relation for Yb-based heavy Fermion systems.
Abstract: We present a theoretical study of the Kadowaki–Woods relation in the orbitally degenerate periodic Anderson model. Based on the Fermi liquid theory, we derive the generalized Kadowaki–Woods relationin the strong coupling limit , \(A\gamma^{-2} \approx 10^{-5} /\frac{1}{2} N(N-1)\) [µΩ cm (mol·K/mJ) 2 ], where A is the coefficient of the T 2 term in the resistivity, γ is the T -linear specific heat coefficient, and N is the f -orbital degeneracy. This result naturally explains the remarkably smaller value of A γ -2 in various orbitally degenerate (mainly Yb-based) heavy Fermion systems, reported by Tsujii et al. [J. Phys.: Condens. Matter 15 (2003) 1993].
TL;DR: In this article, the authors use the eigenstates of the single-particle Hamiltonian as the single particle basis upon which the occupation-number entanglement is defined, in order to characterize quantum correlation caused by interaction.
Abstract: The entanglement between occupation numbers of different single particle basis states depends on coupling between different single particle basis states in the second-quantized Hamiltonian. Thus, in principle, interaction is not necessary for occupation-number entanglement to appear. However, in order to characterize quantum correlation caused by interaction, we use the eigenstates of the single-particle Hamiltonian as the single particle basis upon which the occupation-number entanglement is defined. Using this so-called proper single particle basis, if there is no interaction, the many-particle second-quantized Hamiltonian is diagonalized and thus cannot generate entanglement, while its eigenstates can always be chosen to be non-entangled. If there is interaction, entanglement in the proper single particle basis arises in energy eigenstates and can be dynamically generated. Using the proper single particle basis, we discuss occupation-number entanglement in important eigenstates, especially ground states, of systems of many identical particles, in exploring insights the notion of entanglement sheds on many-particle physics. The discussions on Fermi systems start with Fermi gas, the Hartree–Fock approximation and the electron–hole entanglement in excitations. In the ground state of a Fermi liquid, in terms of the Landau quasiparticles, entanglement becomes negligible. The entanglement in a quantum Hall state is quantified as −fln f − (1 − f)ln(1 − f), where f is the proper fractional part of the filling factor. For BCS superconductivity, the entanglement is a function of the relative momentum wavefunction of the Cooper pair gk, and is thus directly related to the superconducting energy gap, and vanishes if and only if superconductivity vanishes. For a spinless Bose system, entanglement does not appear in the Hartree–Gross–Pitaevskii approximation, but becomes important in the Bogoliubov theory, as a characterization of two-particle correlation caused by the weak interaction. In these examples, the interaction-induced entanglement as calculated is directly related to the macroscopic physical properties.
TL;DR: In this article, the possibility of spin polarization in strongly asymmetric nuclear matter is analyzed within the framework of a Fermi liquid theory with the Skyrme effective interaction, and it is shown that even small admixture of protons strongly decreases the threshold density of spin instability.
Abstract: The possibility of appearance of spin polarized states in strongly asymmetric nuclear matter is analyzed within the framework of a Fermi liquid theory with the Skyrme effective interaction. The zero temperature dependence of the neutron and proton spin polarization parameters as functions of density is found for $SLy4$ and $SLy5$ effective forces. It is shown that at some critical density strongly asymmetric nuclear matter undergoes a phase transition to the state with the oppositely directed spins of neutrons and protons while the state with the same direction of spins does not appear. In comparison with neutron matter, even small admixture of protons strongly decreases the threshold density of spin instability. It is clarified that protons become totally polarized within a very narrow density domain while the density profile of the neutron spin polarization parameter is characterized by the appearance of long tails near the transition density.
TL;DR: In this article, the authors analyzed the spectral properties of the intermediate-valence compound YbAl 3 and showed that the pseudogap and mid-infrared peak result from the indirect and direct gaps, respectively, within the hybridization state.
Abstract: Infrared optical conductivity [σ(ω)] of the intermediate-valence compound YbAl 3 has been measured at temperatures 8–690 K to study its microscopic electronic structures Despite the highly metallic characteristics of YbAl 3 , σ(ω) exhibits a clear pseudogap (strong depletion of spectral weight) of about 60 meV below 40 K It also shows a strong mid-infrared peak centered at ∼025 eV The energy-dependent effective mass and scattering rate of the carriers obtained from the data indicate the formation of a heavy-mass Fermi liquid These characteristic results are discussed in terms of the hybridization states between the Yb 4 f and the conduction electrons It is argued, in particular, that the pseudogap and the mid-infrared peak result from the indirect and direct gaps, respectively, within the hybridization state
TL;DR: In this paper, the electrical resistivity of an antiferromagnetic Kondo compound CeNiGe3 under pressure was measured, and the A and ρ 0 values of the resistivity ρ = ρ0+AT2 in the Fermi liquid relation became maximum around Pc, the A value attaining an extremely large value which was comparable with that in a heavy fermion superconductor CeCu2Si2.
Abstract: We have measured the electrical resistivity of an antiferromagnetic Kondo compound CeNiGe3 under pressure. The Neel temperature initially increases with pressure P up to 3 GPa, then decreases rather steeply with further increasing pressure, and becomes zero at a critical pressure GPa. The A and ρ0 values of the resistivity ρ = ρ0+AT2 in the Fermi liquid relation become maximum around Pc, the A value attaining an extremely large value which is comparable with that in a heavy fermion superconductor CeCu2Si2. Superconductivity is found below 0.48 K in a wide pressure region from 4 to 10 GPa. The upper critical field Hc 2(0) is about 2 T, indicating heavy fermion superconductivity.
TL;DR: An effective theory is developed in which the parameters that enter are an atom-molecule coupling strength and the magnetic moment of the molecular resonance of a Feshbach resonance, demonstrating that the coupling is so strong that many-body effects are appreciable even when the resonance lies at an energy large compared with the Fermi energy.
Abstract: For calculating low-energy properties of a dilute gas of atoms interacting via a Feshbach resonance, we develop an effective theory in which the parameters that enter are an atom-molecule coupling strength and the magnetic moment of the molecular resonance. We demonstrate that, for resonances in the fermionic systems $^{6}\mathrm{Li}$ and $^{40}\mathrm{K}$ that are under experimental investigation, the coupling is so strong that many-body effects are appreciable even when the resonance lies at an energy large compared with the Fermi energy. We calculate a number of many-body effects, including the effective mass and the lifetime of atomic quasiparticles in the gas.
TL;DR: In this article, the authors studied non-Fermi liquid effects due to the exchange of unscreened magnetic gluons in the normal phase of high density QCD by using an effective field theory.
Abstract: We study non-Fermi liquid effects due to the exchange of unscreened magnetic gluons in the normal phase of high density QCD by using an effective field theory. A one-loop calculation gives the well-known result that magnetic gluons lead to a logarithmic enhancement in the fermion self-energy near the Fermi surface. The self-energy is of the form {sigma}({omega}){approx}{omega}{gamma}log({omega}), where {omega} is the energy of the fermion, {gamma}=O(g{sup 2}), and g is the coupling constant. Using an analysis of the Dyson-Schwinger equations we show that, in the weak coupling limit, this result is not modified by higher order corrections even in the regime where the logarithm is large, {gamma}log({omega}){approx}1. We also show that this result is consistent with the renormalization group equation in the high density effective field theory.
TL;DR: In this article, neutrino emission from a normal, ungapped quark phase in the core of a compact star was studied, and it was shown that the emissivity is enhanced by a combination of Fermi liquid and non-Fermi fluid effects.
Abstract: We study neutrino emission from a normal, ungapped, quark phase in the core of a compact star. Neutrino emission from noninteracting quark matter leads to an emissivity that scales as {epsilon}{approx}T{sup 7}. We show that the emissivity is enhanced by a combination of Fermi liquid and non-Fermi liquid effects. Fermi liquid effects lead to an emissivity that scales as {epsilon}{approx}{alpha}{sub s}T{sup 6}, as originally shown by Iwamoto. We demonstrate that non-Fermi liquid effects further enhance the rate, leading to {epsilon}{approx}{alpha}{sub s}{sup 3}T{sup 6}log(m/T){sup 2}, where m is the electric screening scale and m>>T under the conditions found in compact stars. We show, however, that combined with non-Fermi liquid effects in the specific heat the enhancement in the emissivity only leads to a modest reduction in the temperature of the star at late times. Our results confirm existing bounds on the presence of ungapped quark matter in compact stars. We also discuss neutrino emission from superconducting phases with ungapped fermionic excitations.
TL;DR: In this article, the Hertz-Moriya-Millis theory of an antiferromagnetic quantum critical point, in the marginal case of two dimensions, was analyzed up to next-to-leading order in the number of components (N) of the field, and it was shown that logarithmic corrections do not lead to an enhancement of the Landau damping.
Abstract: We analyze the Hertz-Moriya-Millis theory of an antiferromagnetic quantum critical point, in the marginal case of two dimensions $(d=2,z=2).$ Up to next-to-leading order in the number of components (N) of the field, we find that logarithmic corrections do not lead to an enhancement of the Landau damping. This is in agreement with a renormalization-group analysis, for arbitrary N. Hence, the logarithmic effects are unable to account for the behavior reportedly observed in inelastic neutron scattering experiments on ${\mathrm{CeCu}}_{6\ensuremath{-}x}{\mathrm{Au}}_{x}.$ We also examine the extended dynamical mean-field treatment (local approximation) of this theory, and find that only subdominant corrections to the Landau damping are obtained within this approximation, in contrast to recent claims.
TL;DR: In this article, the behavior of heavy-fermion metals is considered and two main types of the behavior when the system is near quantum critical point can be identified as the fermion condensation quantum phase transition (FCQPT).
Abstract: The behavior of the electronic system of heavy-fermion metals is considered. We show that there exist at least two main types of the behavior when the system is near quantum critical point, which can be identified as the fermion condensation quantum phase transition (FCQPT). We show that the first type is represented by the behavior of a highly correlated Fermi liquid, while the second type is depicted by the behavior of a strongly correlated Fermi liquid. If the system approaches FCQPT from the disordered phase, it can be viewed as a highly correlated Fermi liquid which at low temperatures exhibits the behavior of Landau Fermi liquid (LFL). At higher temperatures T, it demonstrates the non-Fermi liquid (NFL) behavior which can be converted into the LFL behavior by the application of magnetic fields B. If the system has undergone FCQPT, it can be considered as a strongly correlated Fermi liquid which demonstrates the NFL behavior even at low temperatures. It can be turned into LFL by applying magnetic fields B. We show that the effective mass M* diverges at the very point that the Neel temperature goes to zero. The B-T phase diagrams of both liquids are studied. We demonstrate that these B-T phase diagrams have a strong impact on the main properties of heavy-fermion metals, such as the magnetoresistance, resistivity, specific heat, magnetization, and volume thermal expansion.
01 Feb 2004
TL;DR: In this article, high-field magnetotransport measurements on BEDT-TTF [(HO)M(CO) ]Y have been carried out, where M = Ga, Cr, and Fe and Y = CHN.
Abstract: We report high-field magnetotransport measurements on β″ -(BEDT-TTF)[(HO)M(CO) ]Y, where M =Ga, Cr, and Fe and Y=CHN. We observe similar Shubnikov-de Haas oscillations in all compounds, attributable to four quasi-two-dimensional Fermi-surface pockets, the largest of which corresponds to a cross-sectional area ≈8.5% of the Brillouin zone. The cross-sectional areas of the pockets are in agreement with the expectations for a compensated semimetal, and the corresponding effective masses are ∼m , rather small compared to those of other BEDT-TTF salts. Apart from the case of the smallest Fermi-surface pocket, varying the M ion seems to have little effect on the overall Fermi-surface topology or on the effective masses. Despite the fact that all samples show quantum oscillations at low temperatures, indicative of Fermi liquid behavior, the sample and temperature dependence of the interlayer resistivity suggest that these systems are intrinsically inhomogeneous. It is thought that intrinsic tendency to disorder in the anions and/or the ethylene groups of the BEDT-TTF molecules leads to the coexistence of insulating and metallic states at low temperatures. A notional phase diagram is given for the general family of β″-(BEDT-TTF) [(HO)M(CO)]Y salts.