Related papers: Double Exchange Models: Self Consistent Renormalis…
We have studied free higher spin gauge fields through an investigation of their Hamiltonian dynamics. Over a flat space-time, their Hamiltonian constraints were identified and solved through the introduction of prepotentials, enjoying both…
We present an asymptotically exact solution of a paradigmatic non-Hermitian model: the disordered interacting fermionic Hatano-Nelson model, or equivalently, the non-Hermitian spin-1/2 XXZ model. We use a renormalization group method suited…
We investigate the effect of periodic driving by an external field on systems with attractive pairing interactions. These include spin systems (like the ferromagnetic XXZ model) as well as ultracold fermionic atoms described by the…
The report discusses the slave-fermion representations of the t-J model and describes another representation, in which fermions and bosons are completely commuting and in which the properties of fermions are directly related to the…
We study integrable models for electrons in metals when the single particle spectrum is discrete. The electron-electron interactions are BCS-like pairing, Coulomb repulsion, and spin exchange coupling. These couplings are, in general,…
A system of interacting spins that are under the influence of spin-polarized currents can be described using a complex functional, or a non-Hermitian (NH) Hamiltonian. We study the dynamics of two exchange-coupled spins on the Bloch sphere.…
We present the detailed formalism of the extremely correlated Fermi liquid theory, developed for treating the physics of the t-J model. We start from the exact Schwinger equation of motion for the Greens function for projected electrons,…
In this paper the exact solution and correlation functions for a double-chain Ising model with multi-spin interactions and symmetric Hamiltonian density are obtained. The study employs the transfer matrix method to derive fundamental…
We propose a simple idea to construct 1D integrable models with impurities. We illustrate the strategy for a supersymmetric $t-J$ Hamiltonian in considerable detail. The impurity comprises the local deformation of the hopping and exchange…
This work is a sequel to our work "The Spin Density Matrix I: General Theory and Exact Master Equations" (eprint arXiv:0708.0644 [cond-mat]). Here we compare pure- and pseudo-spin dynamics using as an example a system of two quantum dots, a…
We investigate doping of a two-orbital chain with mobile $S=1/2$ fermions as a valid model for $\rm Y_{2-x}Ca_xBaNiO_5$. The S=1 spins are stabilized by strong, ferromagnetic (fm) Hund's rule couplings. We calculate correlation functions…
Orbital modeling of two electron spins confined in a double quantum dot is revisited. We develop an extended Hund Mulliken approach that includes excited orbitals, allowing for a triplet configuration with both electrons residing in a…
Using Path Integral Monte Carlo we have calculated exchange frequencies as electrons undergo ring exchanges in a ``clean'' 2d Wigner crystal as a function of density. The results show agreement with WKB calculations at very low density, but…
We introduce various exchange interactions in a model Hamiltonian for Ce$^{3+}$ ions in cubic symmetry with three configurations ($f^0$,$f^1$,$f^2$). With the impurity pseudo spin $S_I=1/2$, our Hamiltonian includes: (i) One-channel…
In this work we present a formal solution of the extended version of the Friedrichs Model. The Hamiltonian consists of discrete and continuum bosonic states, which are coupled to fermions. The simultaneous treatment of the couplings of the…
Building on the mapping of large-$S$ spin chains onto the O($3$) nonlinear $\sigma$ model with coupling constant $2/S$, and on general properties of that model (asymptotic freedom, implying that perturbation theory is valid at high energy,…
The decoration or iteration transformation was widely applied to solve exactly the magnetic spin models in one-dimensional and two-dimensional lattice. The motif of this letter is to extend the decoration transformation approach for models…
We propose a double exchange model to describe the RuO_2 planes of RuSr_2(Eu,Gd)Cu_2O_8. The Ru^+5 ions are described by localized spins, and additional electrons provided by the superconducting CuO_2 planes are coupled ferromagnetically to…
Motivated by cold-atom experiments and a desire to understand far-from-equilibrium quantum transport, we analytically study the dynamics of spin helices in the one-dimensional $XX$ model. We use a Jordan-Wigner transformation to map the…
Studies of the effects of the Hund's rule coupling J_H in multiple orbit impurities or quantum dots using different models have led to quite different predictions for the Kondo temperature T_K as a function of J_H. We show that the…