This work focuses on the theoretical investigation of the coexistence of superconductivity and ferromagnetism in the superconducting homo6s8. Plakida joint institute for nuclear research, 141980 dubna, russia received january 28, 1998 the theory of superconducting pairing due to the exchange and kinematical interactions in the. The green function the mathematics of the retarded and advanced double timetemperature dependent green functions has been given by zubarev 19, and by bonchbruevich and tyablikov20 to whom we refer for details. With the use of a model hamiltonian and retarded double time greens function formalism, we obtain mathematical expressions for spin density wave and superconductivity parameters. Application to the theory of superconductivity 330 7. Greens function method for antiferromagnetism keum hwi lee iowa state university follow this and additional works at.
Localized magnetic impurity states and magnetic moments in a nonmagnetic host metal international organization of scientific research 39 p a g e b. Zubarev fieldtheoretical green functions only in the way the averages are taken. In manybody theory, the term greens function or green function is sometimes used. To get the equation of motion we use the double time temperature. Model study of coexistence of jahnteller distortion. This article reports effects of magnonexciton interaction on magnetic ordering in diluted magnetic semiconductors dms. The defectinduced anharmonic phononelectron problem in hightemperature superconductors has been investigated with the help of double time thermodynamic electron and phonon greens function theory using a comprehensive hamiltonian which includes the contribution due to unperturbed electrons and phonons, anharmonic phonons, impurities, and interactions of electrons and phonons. The general expres sion for the cr peak shape obtained in 0 2 is used in 00 3 and 4 to analyse the halfwidth. For a general description of the double time temperature dependent green function method, see. Using the model of the hamiltonian and green function formalism we obtained two important results expressed by equations 18 and 26. We define retarded and advanced green functions for any 2 operators a and b by. However, in the twotime differentiation method for the green functions.
For a concrete model of the frequency dependence of a memory function, we obtain generalized kettanotype diffusion equation with the spatial and temporal fractality taken into account. The hamiltonian for the heisenberg model is where 2. Citation, d n zubarev, doubletime green functions in statistical physics, sov phys uspekhi, 1960, 3 3, 320345. Bogolyubov, zubarev, tserkovnikov 1957 soviet phys. Double time temperaturedependent green functions 321 3. We used the equation of motion method and the callen decoupling method to evaluate the double time temperature dependent greens functions. Effect of adatomphonon interaction on parameters of.
The green function methods for quantum manybody systems were mainly developed in the 1950s and early 60s. Insulatormetal transition in fe 3 o 4 is analysed on the basis of electronelectron correlation of nearest neighbour sites. Often a hierarchy of characteristic times helps to simplify essentially the solution of the problem. The observed dielectric properties have been explained in. The analytical expression of the ac, equation 15, is parametrized with the parameters of a model intermolecular potential of lennardjones type between pairs of noblegas atoms and a modified diatomic potential sweet and steele 1967. Then the currentvoltage characteristics of the frtd is calculated as a function of temperature and magnetic field by using a. Double time green function technique and zubarev equation of motion approach have been employed. In the quantum context, greens functions are correlation. Double time green functions in statistical physics, zubarev d. By developing a model hamiltonian for the system and using the greens function formalism and equation of motion method, we have obtained expressions for superconducting transition temperature tc, magnetic order temperature tm, superconductivity. Zubarev 1 proposed a theory of superconductivity for an elect.
We have proposed a theoretical model for the coexistence of superconductivity sc, antiferromagnetism afm and jahnteller jt effect in the mean field approximation for iron based superconductors. A formal expression for the spinpolarized current is derived with the keldysh nonequilibriumgreenfunction technique. The greens function for this example is identical to the last example because. Pedagogical introduction to equilibrium greens functions. This paper rederives the bogoliubovsadovnikov classical. The double time green function technique was employed in the zubarevs equation of motion formalism and in order to decouple the hierarchy of higher order green functions harteefock decoupling approximation was assumed. Dielectric properties of kdptype ferroelectric crystals in the presence of external electric. Localized magnetic impurity states and magnetic moments in. Surface phenomenon of chemisorption and its effect on.
Introduction to green functions and manybody perturbation. Reviews of topical problems related content double. Thermodynamic green functions in theory of superconductivity. E with radius of single walled carbon nanotube swcnt was estimated. Green function approach to the theory of superconductivity in the t. For such cases the greens function will depend only on time differences t.
But very often it is convenient to represent it in the energy domain. Ir absorption spectrum of molecules trapped in matrices. Quantum field theory is employed using the double time temperature dependent green function technique to obtain dispersion. Effect of electronphonon interaction and temperature. This method allows us to calculate the cr peak shape parameters taking essential corrections to the born approximation into account. In real time, we will explicitly indicate the timeordered function with a superscript t. Insulatormetal transition in thin films of ferrite fe 3 o. Coexistence of superconductivity and ferromagnetism in. Nauk 71, 71116 may, 1960 contents introduction 320 double time temperaturedependent green functions 321 spectral representations 324 green functions in the theory of irreversible processes 326 perfect quantum gases 328 application to the theory of superconductivity 330. This weeks citation classictm in the paper a brief account is given of the temperaturedependent double time green functions and the simplest applications to the theory of irreversible processes, to the theory of superconductivity, to ferromagnetism, and so on. Here we introduce the numerical calculations for asymmetric sw dispersion relations and inverse proportionality by means of the double time greens function technique, it is useful to study the. Eugene zubarev department of chemistry rice university.
Spindependent current through a ferromagnetic resonant. Eugene zubarev was born on may 4, 1971 and grew up in astrakhan, russia. At the same time, zubarev formulation did not attract much attention in succeeding years, while this hamiltonian can be solved by equation of motion method of zubarevs double time green function of the adatoms self energy and dos density of statesthe greens function used here is the double time greens function applied in condensed. In the present paper the cyclotron resonance cr is analysed using the double time green functions. A new expression for the lattice contribution to the dielectric function is derived using the remarkable zubarev double time green function. A new method for decoupling bogolyubovs chains for. Part of thecondensed matter physics commons this dissertation is brought to you for free and open access by the iowa state university capstones, theses and dissertations at iowa state university.
The coexistence of super conductivity and spin density. Irreducible green functions method and manyparticle interacting. Proceedings of the conference kadanoffbaym equations. Be has the standard meaning of a green function zubarev 1960. Using double time thermal greens function method and dysons equation the collective mode frequencies and widths have been calculated. This weeks citation classictm in the paper a brief account is given of the temperaturedependent double time green functions and the simplest applications to the theory of irreversible processes, to the theory of. In manybody theory, the term green s function or green function is sometimes used interchangeably with correlation function, but refers specifically to correlators of field operators or creation and annihilation operators the name comes from the green s functions used to solve inhomogeneous differential equations, to which they are loosely related. We however, discuss at greater length one aspect seems to us to be very promising, namely, the application of double time temperaturedependent re. Effects of electronelectron and electronphonon optical interactions on the lattice dielectric function of the doped polar semiconductors are investigated. At the same time, zubarev formulated a theory of superconductivity for an electronphonon system based on the equation of motion method for gfs 4. In the applications, the double time retarded and advanced green functions which were. For example, when our system is at equilibrium or when the hamiltonian is timeindependent 7. These parameters lead to the expressions for the dielectric constant and loss tangent. A thermodynamic green functions in superconductivity theory the thermodynamic retarded and advanced double time green functions gfs introduced by bogoliubov and tyablikov 151.
The green function of is the function that satisfies the following conditions. Double time green functions in statistical physics 321 given see also references 50, 53, 54. Green function approach to the theory of superconductivity. A read is counted each time someone views a publication summary such as the title, abstract, and list of authors, clicks on a figure, or views or downloads the fulltext. For the hamiltonian lo, we have solving equations 12 and 14 for a. In manybody theory, the term greens function or green function is sometimes used interchangeably with correlation function, but refers specifically to correlators of field operators or creation and annihilation operators the name comes from the greens functions used to solve inhomogeneous differential equations, to which they are loosely related. Double time green functions in statistical physics. Study of dielectric properties and ultrasonic attenuation.
Since the resistivity is related to the imaginary part of the electron self energy, the expression of the same is evaluated from electron green function by the double time temperature dependant. Ir absorption spectrum of molecules trapped in matrices i. Pe281 greens functions course notes tara laforce stanford, ca 7th june 2006. Zubarevs nonequilibrium statistical operator method in. The modified dependence with and chemisorption energy. Electrons and phonons in high temperature superconductors. The double time temperature dependent retarded green function is given by zubarev. Zubarev in reference 10 and in references cited there. Pe281 greens functions course notes stanford university. A double time zubarev green function technique is used. In general the correlation function of any two operators a and b is given by where p k,t and a.
The model reveals a distinct possibility of the coexistence of magnetic phase and superconductivity, which are two usually irreconcilable cooperative phenomena. It is understood that interaction of the two quasi particles take place in the exciton cloud and consequently the spontaneously ordered localized. Thermodynamic, retarded and advanced green functions gfs introduced by bogoliubov and tyablikov in a seminal work 1 was used soon afterwards in the studies of superconductivity within the bardeencooperschrie. We outline here those features of this technique which are. Then the retarded green function for the fqw, which is needed in the general expression for the transmission coefficient te, is calculated by using zubarevs double timegreenfunction technique. Double time green functions in statistical physics 321 given see also references 50, 53, 54, and 6669. The aim of the present paper is to study the magnon specific heat by using the quasi. Following zubarev 22 we consider the evaluation of greens.
Pedagogical introduction to equilibrium greens functions scielo. Doubletime temperaturedependent green functions 321 3. The double time dependent greens function equal to the change of the average value of some dynamic quantity by the time tand useful because they can be used to describe the effect of retarded interactions and all quantities of physical interest can be derived from them. Introduction to green functions and manybody perturbation theory last updated 20 march 20 contents. Cyclotron resonance of a twodimensional wigner crystal.
Dielectric properties of kdptype ferroelectric crystals. In the paper a brief account is given of the temperaturedependent double time green functions and the simplest applications to the theory of applications to the. Green functions in the theory of irreversible processes 326 5. Thickness dependence of the interfacial dzyaloshinskii. The model is solved by using zubarevs double time greens function technique to.
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