Quantum Spectra of Ferromagnet Metal Nanoparticles Prof. Allan MacDonald Sid W. Richardson Fdn. Regents Chair The University of Texas at Austin Interest in the properties of nanometer scale magnetic particles has grown in recent years, in part because of advances in preparation techniques and in part because of the potential importance of very small magnetic particles for high density information storage technology. It is now possible to reliably realize and study nanoparticles containing of order 1000 atoms using a variety of techniques.\cite{ralph,black,jamet} Fine magnetic particles have traditionally been described using classical (micromagnetic) theories in which the free-energy is expressed, with varying degrees of sophistication, as a functional of the magnetization orientation distribution in the particle. Particles are now small enough that quantum effects are becoming visible. I will discuss some of the issues that arise in considering the quantum physics of magnetic metal nanoparticles.