Magnetocrystalline anisotropy and magnetostriction are fundamental properties of magnetic materials and derive from the fact that the exchange energy which is responsible for the existence of spontaneous magnetization is controlled by the overlap of electron clouds in the crystal. Magnetocrystalline anisotropy derives from the fact that the energy of magnetization is a function of the orientation with respect to the lattice. This leads to "easy" and "hard" directions for magnetization and is a critical parameter controlling the width of domain walls. It is thus clearly important that we have accurate measurements of these parameters if we are to make much progress in our understanding of TRM mechanisms. A major problem is that both constants are known to vary with temperature. In particular, we need values at temperatures near the Curie point as this is where remanence in locked in. The PI will make sure measurements. He will measure both constants for x-values up to 0.8 and temperatures up to the Curie point. His goal is to measure the magnetocrystalline anisotropy constant for several x-values and at temperatures significantly above room temperature. He will use a technique that has seen only limited use in rock magnetism, ferromagnetic resonance.
