Critical behavior of quantum and classical random systems
Thesis/Dissertation
·
OSTI ID:6368728
The effect of random impurities upon the critical behavior of a quantum Heisenberg ferromagnet and superconductor coupled to the electromagnetic field is studied. In the case of the ferromagnet new exact relations for the critical exponents are found and the quantities of interest in the epsilon-expansion are calculated. Quantum to classical crossover behavior occurs. In the case of the superconductor the presence of impurities restores the second order nature of the transition for sufficiently large concentration. The dynamics of classical and quantum spin system coupled to random magnetic fields is studied. In the latter case crossover to classical behavior in certain correlation functions is found. There is an equivalence between the classical and the quantum problems, static exponents and correlation functions are the same as those of the classical pure system in two less dimensions. The dynamical and crossover exponents are calculated up to order epsilon/sup 3/ in the epsilon-expansion.
- Research Organization:
- California Univ., Santa Barbara (USA)
- OSTI ID:
- 6368728
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
36 MATERIALS SCIENCE
360104* -- Metals & Alloys-- Physical Properties
656102 -- Solid State Physics-- Superconductivity-- Acoustic
Electronic
Magnetic
Optical
& Thermal Phenomena-- (-1987)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ANGULAR MOMENTUM
CLASSICAL MECHANICS
CORRELATION FUNCTIONS
ELECTROMAGNETIC FIELDS
FERROMAGNETIC MATERIALS
FUNCTIONS
IMPURITIES
MAGNETIC FIELDS
MAGNETIC MATERIALS
MATERIALS
MECHANICS
PARTICLE PROPERTIES
PHASE TRANSFORMATIONS
QUANTUM MECHANICS
RANDOMNESS
SPIN
SUPERCONDUCTORS
360104* -- Metals & Alloys-- Physical Properties
656102 -- Solid State Physics-- Superconductivity-- Acoustic
Electronic
Magnetic
Optical
& Thermal Phenomena-- (-1987)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ANGULAR MOMENTUM
CLASSICAL MECHANICS
CORRELATION FUNCTIONS
ELECTROMAGNETIC FIELDS
FERROMAGNETIC MATERIALS
FUNCTIONS
IMPURITIES
MAGNETIC FIELDS
MAGNETIC MATERIALS
MATERIALS
MECHANICS
PARTICLE PROPERTIES
PHASE TRANSFORMATIONS
QUANTUM MECHANICS
RANDOMNESS
SPIN
SUPERCONDUCTORS