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.
"TCE dechlorination rates, pathways, and efficiency of nanoscale iron particles with different properties." Yueqiang Liu, Sara A Majetich, Robert D Tilton, David S Sholl, Gregory V Lowry. Environmental science & technology.
"Synthesis and utilization of monodisperse superparamagnetic colloidal particles for magnetically controllable photonic crystals." Xiangling Xu, Gary Friedman, Keith D Humfeld, Sara A Majetich, Sanford A Asher. Chemistry of Materials.
"Superparamagnetism in carbon-coated Co particles produced by the Kratschmer carbon arc process." ME McHenry, SA Majetich, JO Artman, M DeGraef, SW Staley. Physical Review B.
"The 2014 magnetism roadmap." Robert L Stamps, Stephan Breitkreutz, Johan Åkerman, Andrii V Chumak, YoshiChika Otani, Gerrit EW Bauer, Jan-Ulrich Thiele, Martin Bowen, Sara A Majetich, Mathias Kläui, Ioan Lucian Prejbeanu, Bernard Dieny, Nora M Dempsey, Burkard Hillebrands. Journal of Physics D: Applied Physics.
"Preparation and characterization of monodisperse Fe nanoparticles." Dorothy Farrell, Sara A Majetich, Jess P Wilcoxon. The Journal of Physical Chemistry B.
"Magnetic stray fields in nanoscale magnetic tunnel junctions." Sarah Jenkins, Andrea Meo, Luke E Elliott, Stephan K Piotrowski, Mukund Bapna, Roy W Chantrell, Sara A Majetich, Richard FL Evans. Journal of Physics D: Applied Physics.
"Electric field switchable magnetic devices." Jian-Ping Wang, Delin Zhang, Sara A Majetich, Mukund Bapna. US.
"The role of faceting and elongation on the magnetic anisotropy of magnetite Fe3O4 nanocrystals." Roberto Moreno, Samuel Poyser, Daniel Meilak, Andrea Meo, Sarah Jenkins, Vlado K Lazarov, Gonzalo Vallejo-Fernandez, Sara Majetich, Richard FL Evans. arXiv preprint arXiv:1909.02470.
"Effect of Mo capping in sub-100 nm CoFeB-MgO tunnel junctions with perpendicular magnetic anisotropy." Mukund Bapna, Brad Parks, Samuel Oberdick, Hamid Almasi, Congli Sun, Paul Voyles, Weigang Wang, Sara A Majetich. Journal of Magnetism and Magnetic Materials.
"Correlated spin canting in ordered core-shell nanoparticle assemblies." Yumi Ijiri, KL Krycka, Ian Hunt-Isaak, Hillary Pan, J Hsieh, Julie A Borchers, James Jennings Rhyne, Samuel D Oberdick, A Abdelgawad, SA Majetich. Physical Review B.