Quasiparticles In Metals Research Articles

Numerical investigation of the quasi-particles of metals with specific thermodynamic properties at elevated temperatures

The application of the Landau theory of Fermi Liquids to certain thermodynamic properties, like the specific heat of quasi-particles in metals, was investigated in this study. The FORTRAN compiler was used to scientifically coordinate the generation of values of specific heat by writing programs for each thermodynamic property as a function of electron density parameter, temperature, Boltzmann’s constant, and effective mass of the quasi-particle. The results indicate that as the temperature of metals increases, the specific heat of quasi-particles also increases, and the electron density parameter increases for all metals. This suggests that at low densities, the specific heat of quasi-particles is large and there is a large separation between them. Additionally, the ability to absorb heat decreases as the temperature of the quasi-particles increases. The specific heat of quasi-particles calculated in this paper differs greatly from Landau's observations, indicating that the inclusion of the electron density parameter plays a role in the generation of quasi-particles and the observed specific heat of metals. The computed specific heat is close to Laudau’s specific heat but far from the observed specific heat. This research examines the interaction of landau quasi-particles in the overall characteristics of metals and evaluates the reliability of the model used. The results of the calculated specific heat and the actual specific heat demonstrate variations with the model underestimating the specific heat at observed temperatures and higher temperatures.

Magnetic Spin Susceptibility of quasi-particles in metals using the Landau Fermi Liquid Theory

    38  In this work, the magnetic spin susceptibility of quasi-particles in metals were computed for some metals based on the modified Landau Fermi Liquids Theory using the electron density parameter. The results showed that for each metal, the Landau magnetic spin susceptibility of quasi-particles is higher than the computed magnetic spin susceptibility of quasi-particles and experimental values. This may be due to the fact that the Landau parameter must have been over estimated in its application. The computed magnetic spin susceptibility of quasi-particles is in good agreement with the experimental values of metals available with a remarkable agreement at. The better estimation of the magnetic spin susceptibility of quasi-particles using the modified Landau Fermi Liquid theory were compared with available experimental values. This show that the introduction of the electron density parameter in the Landau Fermi Liquid theory is promising in predicting the contribution of quasi-particles to the bulk properties of metals. The magnetic spin susceptibility of quasi-particles for transition metals is higher than most of the magnetic spin susceptibility of quasi-particles for alkali metals. This suggests that the magnetic spin susceptibility is considerably higher for most transition metals due to the incomplete inner electronic shells as more quasi-particles can be excited which enhances their susceptibility than the alkali metals.

Thermally excited quasiparticles in metals, dispersion forces, and the thermal anomaly

We provide a brief review of the contribution of thermally excited carriers to dispersion forces. In a metal, these carriers generate charge and current fluctuations whose spectral frequencies are comparable to [Formula: see text]. They are very likely responsible for the “plasma vs. Drude” anomaly.

Quasi-particle Contribution in Thermal Expansion and Thermal Conductivity in Metals

In this paper the modified Landau theory of Fermi Liquids was used to compute the thermal expansion and thermal conductivity of quasi-particles in metals. The result revealed that as temperature increases the thermal expansion of quasi-particles in metals increases in all the metals investigated. It is also observed that as the electron density parameter increases the thermal expansion of quasi-particles increases. This shows that at low density region the thermal expansion of quasi-particles is large. The result obtained for the thermal conductivity of quasi-particles in metals revealed that for all the metals computed the thermal conductivity of quasi-particles decreases as temperature increases. This seems to suggest that as temperature increases the separation between quasi-particles increases because they are not heavy particles hence, the rate of absorbing heat decreases. The computed thermal expansion and thermal conductivity of quasi-particles are in better agreement with experimental values. This suggests that the introduction of the electron density parameter is promising in predicting the contribution of quasi-particles to the bulk properties of metals. This study revealed the extent to which quasi-particles contribute to the bulk properties of metals, which assisted their potential applications in materials science and engineering development.

Time-resolved collapse and revival of the Kondo state near a quantum phase transition

One of the most successful paradigms of many-body physics is the concept of quasiparticles: excitations in strongly interacting matter behaving like weakly interacting particles in free space. Quasiparticles in metals are very robust objects. Yet, when a system's ground state undergoes a qualitative change at a quantum critical point (QCP), the quasiparticles may disintegrate and give way to an exotic quantum-fluid state of matter. The nature of this breakdown is intensely debated, because the emergent quantum fluid dominates the material properties up to high temperature and might even be related to the occurence of superconductivity in some compounds. Here we trace the dynamics of heavy-fermion quasiparticles in CeCu$_{6-x}$Au$_{x}$ and monitor their evolution towards the QCP in time-resolved experiments, supported by many-body calculations. A terahertz pulse disrupts the many-body heavy-fermion state. Under emission of a delayed, phase-coherent terahertz reflex the heavy-fermion state recovers, with a coherence time 100 times longer than typically associated with correlated metals. The quasiparticle weight collapses towards the QCP, yet its formation temperature remains constant -- phenomena believed to be mutually exclusive. Coexistence in the same experiment calls for revisions in our view on quantum criticality.

Magnetic-field-dependent quasiparticle energy relaxation in mesoscopic wires.

In order to find out if magnetic impurities can mediate interactions between quasiparticles in metals, we have measured the effect of a magnetic field B on the energy distribution function f(E) of quasiparticles in two silver wires driven out of equilibrium by a bias voltage U. In a sample showing sharp distributions at B=0, no magnetic field effect is found, whereas, in the other sample, rounded distributions at low magnetic field get sharper as B is increased, with a characteristic field proportional to U. Comparison is made with recent calculations of the effect of magnetic-impurities-mediated interactions taking into account Kondo physics.

Inclusion of Vertex Corrections in the Self-Consistent Calculation of Quasiparticles in Metals

Based on the Bethe-Salpeter equation and the Ward identity derived from it, we provide a scheme for constructing the vertex function in the self-consistent iteration loop to determine the electron self-energy. The scheme is implemented in the homogeneous electron gas at the sodium density.

Kinetic equation for strongly interacting dense Fermi systems

We review the non-relativistic Green's-function approach to the kinetic equations for Fermi liquids far from equilibrium. The emphasis is on the consistent treatment of the off-shell motion between collisions and on the non-instant and non-local picture of binary collisions. The resulting kinetic equation is of the Boltzmann type, and it represents an interpolation between the theory of transport in metals and the theory of moderately dense gases. The free motion of particles is renormalised by various mean field and mass corrections in the spirit of Landau's quasiparticles in metals. The collisions are non-local in the spirit of Enskog's theory of non-ideal gases. The collisions are moreover non-instant, a feature which is absent in the theory of gases, but which is shown to be important for dense Fermi systems. In spite of its formal complexity, the presented theory has a simple implementation within the Monte-Carlo simulation schemes. Applications in nuclear physics are given for heavy-ion reactions and the results are compared with the former theory and recent experimental data. The effect of the off-shell motion and the non-local and non-instant collisions on the dynamics of the system can be characterised in terms of thermodynamic functions such as the energy density or the pressure tensor. Non-equilibrium counterparts of these functions and the corresponding balance equations are derived and discussed from two points of view. Firstly, they are used to prove the conservation laws. Secondly, the role of individual microscopic mechanisms in fluxes of particles and momenta and in transformations of the energy is clarified.

The observation of resistance oscillations in metals at high magnetic fields using a SQUID

Quantum oscillatory effects provide particularly unambiguous information about the properties of quasiparticles in metals, and have consequently been used for the purpose of understanding the low temperature behaviour of a wide variety of metallic elements and compounds, including the recently discovered heavy fermion materials. Unfortunately, the signals which are produced by these oscillations are often so weak as to be undetectable, because of the high effective masses of the quasiparticles, or the presence of imperfections in the samples, or otherwise. In order to improve our ability to measure these effects, the author has developed a system for the detection of resistance oscillations which uses a SQUID as the amplifying element and which fits inside a toploading dilution refrigerator probe. It has proven possible to use this instrument to investigate very elusive phenomena in samples which have been cooled to 0.02 K in magnetic fields of 13.7 tesla. For example, although no resistance oscillations have previously been seen in aluminum, except under conditions of magnetic breakdown, the new system has made it possible to detect resistance oscillations in this material under relatively arbitrary conditions. In the case of the heavy fermion compound CeRu2Si2, oscillations of 10−9 Ω have been detected against a background resistance of about 10−5 Ω, using excitation currents of around 10−2 A.

Ground-state properties of heavy electrons in U-intermetallics

Recent experimental and theoretical studies dealing with the problem of the occurrence of electrons as heavy Fermi-liquid quasiparticles in metals at low temperatures are reviewed.

CONDITION FOR THE FORMATION OF ACOUSTIC PLASMONS IN METALS

By analysing the dielectric function of an interacting Bloch electron gas, the condition for the formation of acoustic plasmons (AP) as well-defined quasiparticles in metals has been derived. Discussions are given on whether this condition is satisfied for A-15 compounds, with the conclusion that the evidence for the existence of AP as a kind of quasiparticle in these compounds is insufficient until now.