
Introduction
I gave this course from 1998 until 2007 as part of the condensed
matter major option to 4th year students.
There were
7 lectures. (In 2008 it was given by Dr. T. Lancaster.)
Synopsis
 Isolated ions (2 lectures)
Magnetic properties become particularly simple if we
are able to ignore the interactions between ions.
In this case we are able to treat the ions as
effectively ``isolated'' and can discuss
diamagnetism
and paramagnetism. For the latter phenomenon
we revise the derivation of the Langevin and
Brillouin functions outlined in the part A course.
The ions can interact with the crystal
field and this can be probed experimentally
using
magnetic resonance (in particular ESR and NMR).
 Interactions (2 lectures)
Now we turn on the interactions! I will discuss what sort of
interactions there might be, including dipolar
interactions and the different types of exchange
interaction. The interactions lead to various types of
ordered magnetic
structures which can be measured using neutron diffraction.
I will then discuss the Weiss model
of ferromagnetism, antiferromagnetism
and ferrimagnetism and also consider the magnetism of metals.
 Symmetry breaking (3 lectures)
The concept of
broken symmetry is at the heart of condensed matter physics.
The first three lectures aim to demonstrate how the existence of
the solid phase, ferromagnetism and superconductivity, are all
the result of breaking symmetry. The consequences of breaking
symmetry are that systems show some kind of rigidity (in the case
of ferromagnetism this is permanent magnetism),
low temperature elementary excitations (in the case of
ferromagnetism these are spin waves, also known
as magnons),
and defects (in the case of ferromagnetism these are
domain walls).
These concepts are explored in the context of lowdimensional
magnetism.

 Courserelated links

 Magnetismrelated links

(Updated: May 2008)
