My thesis concerns two areas of current research in magnetism, with the common experimental
technique of elastic and inelastic neutron scattering on powders and single crystals.
The first topic is concerned with rare earth intermetallic compounds with unfilled 4f shells.
When a rare earth element with an unfilled shell is placed in an environment with surrounding
charges, the crystal electric field acts to lift the J-fold degeneracy. Determination
of the Crystal Electric Field (CEF) ground state and excited states are important to understand
the complex and interesting low temperature phase diagrams these compounds
exhibit. This will be discussed for the rare earth intermetallic compound TmGa3. The
other area of my thesis concerns one dimensional Heisenberg antiferromagnetic quantum
chains systems. Due to the one-dimensional lattice and low spin, quantum fluctuations play
an important role in these systems. From the nature of the lattice, the interactions could
give rise to magnetic frustration, resulting in interesting ground states. I will discuss results
on the binary halides CuCl2, CuBr2 and on the quaternary oxide LiCuVO4. To measure the
thermal properties of the investigated systems, a quasi-adiabatic Nernst type calorimeter
was constructed and commissioned. I will describe the design and the properties of the
A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of the degree of Doctor of Philosophy at Loughborough University.