Search results for "quasiparticle"
showing 10 items of 280 documents
Mixing of Two-Quasiparticle Configurations
2007
In this chapter we discuss configuration mixing of two-quasiparticle states. It is caused by the residual interaction remaining beyond the quasiparticle mean field defined in Chap. 13. We derive the equations of motion by the EOM method developed in Sect. 11.1. To accomplish this we need to express the residual Hamiltonian in terms of quasiparticles.
Energy gap of intermediate-valentSmB6studied by point-contact spectroscopy
2001
We have investigated the intermediate valence narrow-gap semiconductor ${\mathrm{SmB}}_{6}$ at low temperatures using both conventional spear-anvil type point contacts as well as mechanically controllable break junctions. The zero-bias conductance varied between less than $0.01 \ensuremath{\mu}\mathrm{S}$ and up to 1 mS. The position of the spectral anomalies, which are related to the different activation energies and band gaps of ${\mathrm{SmB}}_{6},$ did not depend on the the contact size. Two different regimes of charge transport could be distinguished: Contacts with large zero-bias conductance are in the diffusive Maxwell regime. They had spectra with only small nonlinearities. Contacts…
Isotope Effects and Collective Excitations
1983
Isotopic substitution in the aqueous solvent is discussed as an effective method for probing the role of solvent dynamics in the stability of biomolecular conformation.
Collective Excitations in Simple Liquids
2014
The dynamics of simple liquid is discussed by starting from the linearized Navier-Stokes equations. Using these equations expicit formulas for the density- and current-correlation functions are given. Mode-coupling theory is introduced, which gives a constitutive equation between the current-relaxation memory function and the density correlation function. This theory is shown to accurately describe the collective-excitation behavior of simple liquids like liquid metals.
Plasmon mass scale and quantum fluctuations of classical fields on a real time lattice
2018
Classical real-time lattice simulations play an important role in understanding non-equilibrium phenomena in gauge theories and are used in particular to model the prethermal evolution of heavy-ion collisions. Above the Debye scale the classical Yang-Mills (CYM) theory can be matched smoothly to kinetic theory. First we study the limits of the quasiparticle picture of the CYM fields by determining the plasmon mass of the system using 3 different methods. Then we argue that one needs a numerical calculation of a system of classical gauge fields and small linearized fluctuations which correspond to quantum fluctuations, in a way that keeps the separation between the two manifest. We demonstra…
Thermodynamic, dynamic and transport properties of quantum spin liquid in herbertsmithite from experimental and theoretical point of view
2019
In our review we focus on the quantum spin liquid, defining the thermodynamic, transport and relaxation properties of geometrically frustrated magnets (insulators) represented by herbertsmithite $\rm ZnCu_{3}(OH)_6Cl_2$.
Magnetic-field-induced reentrance of Fermi-liquid behavior and spin-lattice relaxation rates in
2009
Abstract A strong departure from Landau–Fermi liquid (LFL) behavior have been recently revealed in observed anomalies in both the magnetic susceptibility χ and the muon and 63Cu nuclear spin-lattice relaxation rates 1 / T 1 of YbCu 5 − x Au x ( x = 0.6 ). We show that the above anomalies along with magnetic-field-induced reentrance of LFL properties are indeed determined by the dependence of the quasiparticle effective mass M ∗ on magnetic field B and temperature T and demonstrate that violations of the Korringa law also come from M ∗ ( B , T ) dependence. We obtain this dependence theoretically utilizing our approach based on fermion condensation quantum phase transition (FCQPT) notion. Ou…
Energy scales and magnetoresistance at a quantum critical point
2009
The magnetoresistance (MR) of CeCoIn_5 is notably different from that in many conventional metals. We show that a pronounced crossover from negative to positive MR at elevated temperatures and fixed magnetic fields is determined by the scaling behavior of quasiparticle effective mass. At a quantum critical point (QCP) this dependence generates kinks (crossover points from fast to slow growth) in thermodynamic characteristics (like specific heat, magnetization etc) at some temperatures when a strongly correlated electron system transits from the magnetic field induced Landau Fermi liquid (LFL) regime to the non-Fermi liquid (NFL) one taking place at rising temperatures. We show that the abov…
Molecular quenching and relaxation in a plasmonic tunable system
2008
Molecular fluorescence decay is significantly modified when the emitting molecule is located near a plasmonic structure. When the lateral sizes of such structures are reduced to nanometer-scale cross sections, they can be used to accurately control and amplify the emission rate. In this Rapid Communication, we extend Green's dyadic method to quantitatively investigate both radiative and nonradiative decay channels experienced by a single fluorescent molecule confined in an adjustable dielectric-metal nanogap. The technique produces data in excellent agreement with current experimental work.
Localized surface plasmons on a torus in the nonretarded approximation
2005
International audience; The dispersion relations and field patterns of the localized surface plasmons of a torus are derived analytically in toroidal coordinates in the nonretarded approximation. Numerical calculations are provided in order to identify the conditions under which a toroidal nanostructure supports a significant magnetic dipole moment at optical frequencies.