  We study a single electron transistor (SET) based upon a II-VI semiconductor
quantum dot doped with a single Mn ion. We present evidence that this system
behaves like a quantum nanomagnet whose total spin and magnetic anisotropy
depend dramatically both on the number of carriers and their orbital nature.
Thereby, the magnetic properties of the nanomagnet can be controlled
electrically. Conversely, the electrical properties of this SET depend on the
quantum state of the Mn spin, giving rise to spin-dependent charging energies
and hysteresis in the Coulomb blockade oscillations of the linear conductance.
