Accession Number : ADA349716


Title :   Spin and Magnetism: Two Transfer Matrix Formulations of a Classical Heisenberg Ring in a Magnetic Field.


Descriptive Note : Master's Thesis


Corporate Author : NAVAL POSTGRADUATE SCHOOL MONTEREY CA


Personal Author(s) : Franciose, Randall J.


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a349716.pdf


Report Date : JUN 1998


Pagination or Media Count : 62


Abstract : Nanometer scale fabrication and experimental investigations into the magnetic properties of mesoscopic molecular clusters have specifically addressed the need for theoretical models to as certain thermodynamic properties. Technological applications germane to these inquiries potentially include minimum scale ferromagnetic data storage and quantum computing. The one-dimensional nearest neighbor Heisenberg spin system accurately models the energy exchange of certain planar rings of magnetic ions. Seeking the partition function from which a host of thermodynamic quantities may be obtained, this thesis contrasts two transfer matrix formulations of a classical Heisenberg ring in a magnetic field. Following a discussion of the transfer matrix technique in an Ising model and a review of material magnetic characteristics, a Heisenberg Hamiltonian development establishes the salient integral eigenvalue equation. The 1975 technique of Blume et al turns the integral equation into a matrix eigenvalue equation using Gaussian numerical integration. This thesis alternatively proposes an exactly formulated matrix eigenvalue equation, deriving the matrix elements by expanding the eigenvectors in a basis of the spherical harmonics. Representing the energy coupling of the ring to a magnetic field with symmetric or asymmetric transfer operators develops pragmatically distinctive matrix elements; the asymmetric yielding a simpler expression. Complete evaluation will require follow-on numerical analysis.


Descriptors :   *MAGNETIC FIELDS , *THERMODYNAMIC PROPERTIES , *MATRIX THEORY , MATHEMATICAL MODELS , COUPLING(INTERACTION) , IONS , MAGNETIC PROPERTIES , QUANTUM THEORY , NUMERICAL ANALYSIS , SPHERICAL HARMONICS , EIGENVECTORS , THESES , FABRICATION , EIGENVALUES , ENERGY TRANSFER , CLUSTERING , PLANAR STRUCTURES , DATA STORAGE SYSTEMS , SPINNING(MOTION) , INTEGRAL EQUATIONS , FERROMAGNETIC MATERIALS , HAMILTONIAN FUNCTIONS.


Subject Categories : ELECTRICITY AND MAGNETISM
      NUCLEAR PHYSICS & ELEMENTARY PARTICLE PHYSICS
      THERMODYNAMICS


Distribution Statement : APPROVED FOR PUBLIC RELEASE