scholarly journals Bosonización de líquidos de Luttinger: interacciones con inversión de spin y acoplamiento spin-órbita

2004 ◽  
Author(s):  
◽  
Carlos Aníbal Iucci
Keyword(s):  
Degrees Of Freedom ◽  
Condensed Matter ◽  
Harmonic Approximation ◽  
Quantum Field Theories ◽  
Quantum Field ◽  
Spin Orbit ◽  
Luttinger Liquids ◽  
Self Consistent ◽  
Non Local ◽  
Spin Orbit Interactions

In this thesis we present contributions in the field of the applications of quantum field theories techniques to condensed matter models. In chapter 3 we investigate on the non covariant fermionic determinant and its connection to Luttinger liquids. We address the problem of the regularization of the theory. In chapter 4 we treat spin flipping interactions in the non local Thirring model and we obtain an effective bosonic actions that describe separated spin and charge degrees of freedom. In chapter 4 we apply the self consistent harmonic approximation to previously derived bosonic action and we obtain potential depending equations for the spectrum gap. In chapter 5 we include spin-orbit couplings and compute correlations functions. We show that the spin orbit interactions modify the exponents and the phase diagram of the system and makes new susceptibilities diverge for low temperature. Finally in chapter 6 we summarize the main results and the conclusions.

Physics of Spin-Orbit-Coupled Oxides

2021 ◽  
Author(s):  
Gang Cao ◽  
Lance DeLong
Keyword(s):  
Giant Magnetoresistance ◽  
Degrees Of Freedom ◽  
High Temperature Superconductivity ◽  
Transition Element ◽  
Spin Orbit ◽  
Transition Elements ◽  
Crystalline Electric Field ◽  
Magnetic Exchange ◽  
Spin Orbit Interactions ◽  
Strong Spin

Prior to 2010, most research on the physics and chemistry of transition metal oxides was dominated by compounds of the 3d-transition elements such as Cr, Mn, Fe, Co, Ni, and Cu. These materials exhibited novel, important phenomena that include giant magnetoresistance in manganites, as well as high-temperature superconductivity in doped La2CuO4 and related cuprates. The discovery in 1994 of an exotic superconducting state in Sr2RuO4 shifted some interest toward ruthenates. Moreover, the realization in 2008 that a novel variant of the classic Mott metal-insulator transition was at play in Sr2IrO4 provided the impetus for a burgeoning group of studies of the influence of strong spin-orbit interactions in “heavy” (4d- and 5d-) transition-element oxides. This book reviews recent experimental and theoretical evidence that the physical and structural properties of 4d- and 5d-oxides are decisively influenced by strong spin-orbit interactions that compete or collaborate with comparable Coulomb, magnetic exchange, and crystalline electric field interactions. The combined effect leads to unusual ground states and magnetic frustration that are unique to this class of materials. Novel couplings between the orbital/lattice and spin degrees of freedom, which lead to unusual types of magnetic order and other exotic phenomena, challenge current theoretical models. Of particular interest are recent investigations of iridates and ruthenates focusing on strong spin-orbit interactions that couple the lattice and spin degrees of freedom.

Current Control of Structural and Physical Properties in Spin-Orbit- Coupled Mott Insulators

2021 ◽  
pp. 135-158
Author(s):  
Gang Cao ◽  
Lance E. DeLong
Keyword(s):  
Physical Properties ◽  
Transition Metal Oxides ◽  
Information Technologies ◽  
Degrees Of Freedom ◽  
Electrical Current ◽  
Current Control ◽  
Mott Insulators ◽  
Spin Orbit ◽  
Electrical Currents ◽  
Spin Orbit Interactions

Electrical current as a means to control structural and related physical properties has been recognized only recently. The application of small electrical currents in sensitive detector and control applications, and in information technologies, is often preferable to other external stimuli. However, until recently it has not been widely accepted that electrical current can readily couple to the lattice, orbital, and spin degrees of freedom. Mounting experimental evidence has indicated that a combination of strong spin-orbit interactions and a distorted crystal structure in magnetic Mott insulators may be sufficient for electrical current to control structural and related properties. Current control of quantum states in 4d- and 5d-transition metal oxides has therefore rapidly expanded as a key research topic. This chapter presents two model systems, Ca2RuO4 and Sr2IrO4, in which applied current effectively controls the lattice, and thus the physical properties.

scholarly journals QUANTUM FIELD THEORY ON CURVED BACKGROUNDS — A PRIMER

2013 ◽  
Vol 28 (17) ◽  
pp. 1330023 ◽  
Author(s):  
MARCO BENINI ◽  
CLAUDIO DAPPIAGGI ◽  
THOMAS-PAUL HACK
Keyword(s):  
Field Theory ◽  
Quantum Field Theory ◽  
Hilbert Space ◽  
Degrees Of Freedom ◽  
Algebraic Approach ◽  
Quantum Field Theories ◽  
Quantum Field ◽  
System A ◽  
Step Procedure ◽  
Free Fields

Goal of this paper is to introduce the algebraic approach to quantum field theory on curved backgrounds. Based on a set of axioms, first written down by Haag and Kastler, this method consists of a two-step procedure. In the first one, it is assigned to a physical system a suitable algebra of observables, which is meant to encode all algebraic relations among observables, such as commutation relations. In the second step, one must select an algebraic state in order to recover the standard Hilbert space interpretation of a quantum system. As quantum field theories possess infinitely many degrees of freedom, many unitarily inequivalent Hilbert space representations exist and the power of such approach is the ability to treat them all in a coherent manner. We will discuss in detail the algebraic approach for free fields in order to give the reader all necessary information to deal with the recent literature, which focuses on the applications to specific problems, mostly in cosmology.

RENORMALIZATION AND BOLTZMANN EQUATIONS IN THERMAL QUANTUM FIELD THEORY

1995 ◽  
Vol 10 (11) ◽  
pp. 1693-1700 ◽  
Author(s):  
H. CHU ◽  
H. UMEZAWA
Keyword(s):  
Boltzmann Equation ◽  
Renormalization Scheme ◽  
Quantum Field Theories ◽  
Quantum Field ◽  
Boltzmann Equations ◽  
Self Energy ◽  
Spatially Inhomogeneous ◽  
Thermo Field Dynamics ◽  
Self Consistent ◽  
Consistent Manner

The renormalization scheme in nonequilibrium thermal quantum field theories is reexamined. Instead of the self-energy diagonalization scheme, we propose to diagonalize Green’s function at equal time. This eliminates the problem of on-shell definition related to time-dependent energies and spatially inhomogeneous situations, and yields a Boltzmann equation that contains memory effect. The new diagonalization scheme and the derivation of the Boltzmann equation from it can be applied to any thermal situation. It allows the treatment of a nonequilibrium problem beyond perturbational calculations in a self-consistent manner. The results are applicable to both thermo field dynamics and the closed time path formalism.

Spin-orbit interactions from self consistent field wavefunctions

1993 ◽  
Vol 80 (3) ◽  
pp. 479-502 ◽  
Author(s):  
Michael J. Bearpark ◽  
Nicholas C. Handy ◽  
Paolo Palmieri ◽  
Riccardo Tarroni
Keyword(s):  
Spin Orbit ◽  
Consistent Field ◽  
Self Consistent ◽  
Self Consistent Field ◽  
Spin Orbit Interactions

scholarly journals Frame covariant formalism for fermionic theories

2021 ◽  
Vol 81 (7) ◽  
Author(s):  
Kieran Finn ◽  
Sotirios Karamitsos ◽  
Apostolos Pilaftsis
Keyword(s):  
Effective Action ◽  
Degrees Of Freedom ◽  
Field Theories ◽  
Quantum Field Theories ◽  
Quantum Field ◽  
Covariant Formalism ◽  
Classical Action ◽  
Proper Definition ◽  
Definition Of ◽  
Standing Problem

AbstractWe present a frame- and reparametrisation-invariant formalism for quantum field theories that include fermionic degrees of freedom. We achieve this using methods of field-space covariance and the Vilkovisky–DeWitt (VDW) effective action. We explicitly construct a field-space supermanifold on which the quantum fields act as coordinates. We show how to define field-space tensors on this supermanifold from the classical action that are covariant under field reparametrisations. We then employ these tensors to equip the field-space supermanifold with a metric, thus solving a long-standing problem concerning the proper definition of a metric for fermionic theories. With the metric thus defined, we use well-established field-space techniques to extend the VDW effective action and express any fermionic theory in a frame- and field-reparametrisation-invariant manner.

Sign in / Sign up

Export Citation Format

Share Document