Local Spin Anisotropy Effects upon the Magnetization of Single Molecule Dimers

We present an exactly solvable model of equal spin $s_1$ single molecule magnetic dimers. The spins within each dimer interact via the Heisenberg and the most general quadratic global and local anisotropic spin exchange interactions, and with the magnetic induction ${\bf B}$. For antiferromagnetic couplings and $s_1>1/2$, the low temperature magnetization ${\bf M}({\bf B})$ exhibits a rich variety of steps of unequal width, the structure and anisotropy of which depend upon the various local anisotropic spin exchange energies. Specific numerical results for Fe2 $s_1=5/2$ dimers will be presented.