EXCHANGE ENERGY AND MAGNETISM OF RARE - EARTH METALS
EXCHANGE ENERGY AND MAGNETISM OF RARE - EARTH METALS
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Date
1997-02
Authors
Mai - Unguwa, Hamisu
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Abstract
In our study of Ferromagnetism, we have used the Heisenberg model as a general
frame work. The indirect exchange model of Ruthermann - Kittel interaction (originally
proposed for atomic nuclei) is applied to the case of Rare - earth Ferromagnetic systems. This
exchange energy (between spins) is calculated as a second order perturbation. The behaviour
of the Weiss Mean Field (WMF) which is an approximation of the exchange interaction and
the energy spectrum of the spin are presented in graphical form.
Calculation of the WMF and the energy against the Fermi Wave Vector (KF) are performed
for simple cubic lattice (SC), Body-Centred Cubic lattice (BCC) and Face-Centred Cubic
lattice (FCC) configuration along the [100] direction. The results obtained are in good
agreement with those found in the literature. The extension to Hexagonal Closed Pack (HCP)
which is the common structure in Rare - earth metals is the major contribution of this project.
The plots of the WMF and energy against KF along [100], [110] and [111] directions give
regions of positive values, thereby satisfying the main condition for Ferromagnetic properties.
Description
A THESIS SUBMITTED TO THE POST GRADUATE SCHOOL OF
AHMADU BELLO UNIVERSITY, ZARIA IN PARTIAL FULFILMENT
FOR THE AWARD OF THE MASTER OF SCIENCE DEGREE IN
PHYSICS.
Keywords
EXCHANGE ENERGY,, MAGNETISM,, RARE - EARTH METALS