Asphericity in the Fermi Surface and Fermi Energy of Na-K, Na-Rb and Na-Cs Binary Alloys

Detailed theoretical investigations into asphericity in the Fermi surface (FS) and Fermi energy (FE) ofNa1_xKx, Na1_xRbx, and Na1_xCsx binary solid solutions are carried out for the first time. The alloying behavior ofthe K, Rb, and Cs with the Na generates the Fermi surface distortion (FSD) of bce simple metals. The FS of Na-K,Na-Rb, and Na-Cs solid solution is a distorted sphere with the largest deviation along [110]. We have found that theimpact of local-field correction function on FSD is maximun at [100] point and minimum at [111] point. The exchangeand correlation effect is found to suppress the value of FE.     

Instabilities of a Fermi Gas with Nested Fermi Surfaces

The nesting of the Fermi surfaces of an electron and a hole pocket separated by a vector Q commensurate with the lattice in conjunction with the interaction between the quasiparticles can give rise to a rich phase diagram. Of particular importance is itinerant antiferromagnetic order in the context of pnictides and heavy fermion compounds. By mismatching the nesting the order can gradually be suppressed and as the Néel temperature tends to zero a quantum critical point is obtained. A superconducting dome above the quantum critical point can be induced by the transfer of pairs of electrons between the pockets. The conditions under which such a dome arises are studied. In addition numerous other phases may arise, e.g. charge density waves, non‐Fermi liquid behavior, non‐s‐wave superconductivity, Pomeranchuk instabilities of the Fermi surface, nematic order, and phases with persistent orbital currents.     

Particle physics implications for CoGeNT, DAMA, and Fermi

Recent results from the CoGeNT Collaboration (as well as the annual modulation reported by DAMA/LIBRA) point toward dark matter with a light (5-10 GeV) mass and a relatively large elastic scattering cross section with nucleons (σ∼¹⁰−40 cm²). In order to possess this cross section, the dark matter must communicate with the Standard Model through mediating particles with small masses and/or large couplings. In this Letter, we explore with a model-independent approach the particle physics scenarios that could potentially accommodate these signals. We also discuss how such models could produce the gamma rays from the Galactic Center observed in the data of the Fermi Gamma-Ray Space Telescope. We find multiple particle physics scenarios in which each of these signals can be accounted for, and in which the dark matter can be produced thermally in the early Universe with an abundance equal to the measured cosmological density.     

Fermi surface effect on intrinsic Lorenz number of Fermi liquids

We investigate a Fermi surface effect on the ideal Lorenz ratio of an anisotropic Fermi liquid caused by the onset of Umklapp scatterings. After discussing simple models by way of illustration, we present numerical results for transition metals, and indicate a material with a simple Fermi surface like sodium cobaltite as a possible candidate to observe the effect.     

Extended Fermi coordinates

We extend the notion of Fermi coordinates to a generalized definition in which the highest orders are described by arbitrary functions. From this definition rises a formalism that naturally gives coordinate transformation formulae. Some examples are developed in order to discuss the physical meaning of Fermi coordinates.     

Fermi acceleration revisited

Mappings that have been used to describe the Fermi acceleration mechanism are examined. It is shown that results which appear to be contradictory are due to differences in the mapping equations. For those mappings that can be locally approximated by the standard mapping, the value of the nonlinear parameter of the standard mapping, for which the last isolating KAM surface exists, can be used to predict the loss of KAM stability with action for the more general mappings. Previous results of the variation in the density distribution in the stochastic region of the phase space, averaged over phases, is shown to be consistent with the ergodic hypothesis. Fine scale structure of the mappings is found to be model dependent. The standard mapping is a member of a class of mappings which retains some KAM trajectories at arbitrarily large nonlinearity. This feature is not generic to a wider class of mappings discussed in this paper. The stability of two-iteration fixed points are discussed in detail, including the bifurcation sequence for one type of mapping.     

Fermi, Majorana and the Statistical Model of Atoms

We give an account of the appearance and first developments of the statistical model of atoms proposed by Thomas and Fermi, focusing on the main results achieved by Fermi and his group in Rome. Particular attention is addressed to the unknown contribution to this subject by Majorana, anticipating some important results reached later by leading physicists.     

Trimers, molecules, and polarons in mass-imbalanced atomic Fermi gases

We consider the ground state of a single "spin-down" impurity atom interacting attractively with a "spin-up" atomic Fermi gas. By constructing variational wave functions for polarons, molecules, and trimers, we perform a detailed study of the transitions between these dressed bound states as a function of mass ratio r=m↑/m↓ and interaction strength. Crucially, we find that the presence of a Fermi sea enhances the stability of the p-wave trimer, which can be viewed as a Fulde-Ferrell-Larkin-Ovchinnikov molecule that has bound an additional majority atom. For sufficiently large r, we find that the transitions lie outside the region of phase separation of the imbalanced Fermi gas and should thus be observable in experiment, unlike the well-studied equal-mass case.     

Chern numbers,quaternions, and Berry's phases in Fermi systems

Yes, but some parts are reasonably concrete.On leave form Physics Dept., Technion, Haifa, 32000, IsraelResearch partially supported by NSF Grant DMS-8801918     

Fermi surface,magnetic, and superconducting properties in actinide compounds

The de Haas–van Alphen effect, which is a powerful method to explore Fermi surface properties, has been observed in cerium, uranium, and nowadays even in neptunium and plutonium compounds. Here, we present the results of several studies concerning the Fermi surface properties of the heavy fermion superconductors UPt₃ and NpPd₅Al₂, and of the ferromagnetic pressure-induced superconductor UGe₂, together with those of some related compounds for which fascinating anisotropic superconductivity, magnetism, and heavy fermion behavior has been observed.     

A Two Dimensional Fermi Liquid. Part 3: The Fermi Surface

We show that the particle number density derived from the thermodynamic Greens function at temperature zero constructed in the second part of this series has a jump across the Fermi curve, a basic property of a Fermi liquid. We further show that the two particle thermodynamic Greens function at temperature zero has the regularity behavior expected in a Fermi liquid.Research supported in part by the Natural Sciences and Engineering Research Council of Canada and the Forschunginstitut für Mathematik, ETH Zürich.     

Fermi surface of LaAg

Electronic structure, especially the Fermi surface, is calculated for the intermetallic rare-earth compound LaAg, known to show the structural phase transition when In is substituted for Ag, by a self-consistent fully-relativistic APW method with the exchange-correlation potential in a local-density approximation. The Fermi surface is found to consist of large hole and electron sheets as well as small hole and electron sheets. This result confirms well the theoretical prediction by Niksch et al. (1987). These Fermi surface sheets are found to explain the experimental results for the de Haas-van Alphen effect by Niksch et al. (1987) and Motoki et al. (1995) reasonably well. But, the frequency branches originating from the large hole sheet have been observed only partially. Local curvature of the large hole sheet is investigated as a possible origin of the disappearance of these frequency branches.     

Fermi substructure of space-time

If space-time possesses a Fermi substructure, then the canonical quantization of the space-time and the Fermi coordinates of a relativistic point particle must be mutually consistent. We show that the Fermi substructure meets this requirement. We express the generators of the Lorentz group in terms of the Fermi coordinates and momenta and consider their coordinate representation.     

Surfaces de Fermi,profil Compton et effets a N-corps

Nous montrons théoriquement qu'il est possible de déterminer les surfaces de Fermi à partir de profils Compton de métaux même lorsque l'on tient compte des effets à N-corps dans leur totalité.     

Fermi and electromagnetic mass

Fermi’s analysis of the contribution of the electromagnetic field to the inertial mass of the classical electron within special relativity is brought to its logical conclusion, leading to the conservation of the total 4-momentum of the field plus mechanical mass system as seen by the sequence of inertial observers in terms of which the accelerated electron is momentarily at rest.     

Fermi gas of atoms

A rapidly developing field, experimental physics of ultracold gases of Fermi atoms, is briefly reviewed. The contribution of this field to fundamental physics is shown along with connection to other fields which explore systems of Fermi particles. The basic parameters of atomic Fermi gas are described together with its unique properties and advantages and disadvantages in comparison to other Fermi systems. The prospects of this field and its short history are considered. Research groups working in this field are listed.     

Monopoles admit Fermi statistics

't Hooft-Polyakov monopoles are shown to admit Fermi statistics in the sense of Finkelstein.