My research focuses on magnetic nanoparticles that have very uniform sizes, and we study their fundamental behavior, as well as possible applications in data storage media, permanent magnets, and biomedicine. One of the consequences of this monodispersity is that the particles can then self-assemble into arrays (shown below), just as atoms come together to form a crystal. We are investigating the collective behavior of the nanoparticle arrays that are analogous to those in crystals. Isolated iron atoms do not interact with each other and are paramagnetic, but in an iron crystal the interactions lead to ferromagnetism. Superparamagnetic-to-ferromagnetic and insulator-to-metal phase transitions are expected as the nanoparticles are brought closer together. We have also developed a method to replace the surfactant coating the particles with an inorganic matrix, and are exploring methods that exploit this approach to prepare functional nanocomposites.

More details about current research projects, current group members, and financial support can be found at the Majetich group home page: http://www.andrew.cmu.edu/user/sm70

Selected Publications

S. Majetich, J. E. Rives, and R. S. Meltzer, “Phonon Dynamics in Alexandrite and Ruby”, Phys. Rev. B38, 11075 (1988).

S. Majetich, D. Boye, J. E. Rives, and R. S. Meltzer, “Spectroscopy of the 2E Excited State of Cr3+ in Alexandrite", J. Lumin. 40&41, 307 (1988).

D. Boye, S. Majetich, J. E. Rives, R. S. Meltzer, and R. S. Macfarlane “Phonon-Induced Optical Dephasing in Alexandrite by Thermal and Non-Equilibrium Phonons”, XVth International Quantum Electronics Conference Technical  Digest  Series  21, 198 (1987).

S. Majetich, J. E. Rives, and R. S. Meltzer, “Dynamics of 38 cm-1 Phonons in Alexandrite", in Phonon Scattering in Condensed Matter V, A. C. Anderson and J. P.Wolfe, eds., Springer-Verlag, Berlin, 1986.

D. J. Sox, S. Majetich, J. E. Rives, and R. S. Meltzer, “Excited State Electron Spin Resonance Using Non-Resonant Fluorescence Line Narrowing”, Journal de Physique 46, C7-493 (1985).