Sara Majetich-Dept of Physics - Carnegie Mellon University

Sara Majetich

Professor, Physics

Office: Wean Hall 6404
Phone: 412-268-3105
Fax: 412-681-0648

Education

Ph.D., University of Georgia

Research

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://nano.phys.cmu.edu/

Selected Publications

  • S. K. Piotrowski et al., Size and voltage dependence of effective anisotropy in sub-100-nm perpendicular magnetic tunnel junctions, Phys. Rev. B 94, 014404 (2016)
  • A. Hevroni, M. Bapna, S. Piotrowski, S. A. Majetich, G. Markovich, Tracking the Verwey transition in single magnetite nanocrystals by variable-temperature scanning tunneling microscopy, J. Phys. Chem. Lett. 7, 1661 (2016)
  • L. Tryputen et al., Patterning of sub-50 nm perpendicular CoFeB/MgO-based magnetic tunnel junctions, Nanotechnology 27, 185302 (2016)
  • A. M. Abdelgawad, S. D. Oberdick, S. A. Majetich, Formation of FePt nanodots by wetting of nanohole substrates, AIP Adv., 6, 056114 (2016)
  • M. Bapna, S. K. Piotrowski, S. D. Oberdick, M. Li, C.-L. Chien, S. A. Majetich,  Magnetostatic effects on switching in small magnetic tunnel junctions, Appl. Phys. Lett. 108, 022406 (2016)
  • V. K. Sakharov, R. A. Booth, S. A. Majetich, High-frequency permeability of Ni and Co particle assemblies, Journal of Applied Physics 115, 17 (2014)
  • Samuel D. Oberdick, Sara A. Majetich, Electrophoretic Deposition of Iron Oxide Nanoparticles on Templates, The Journal of Physical Chemistry C 117, 18709 (2013)
  • Tianlong Wen, Ryan A. Booth, Sara A. Majetich, Ten-Nanometer Dense Hole Arrays Generated by Nanoparticle Lithography, Nano Letters 12, 5873 (2012)
  • Tianlong Wen, Sara A. Majetich, Ultra-Large-Area Self-Assembled Monolayers of Nanoparticles, ACS Nano 5, 8868 (2011)
  • S. A. Majetich, T. Wen, R. A. Booth, Functional Magnetic Nanoparticle Assemblies: Formation, Collective Behavior, and Future Directions, ACS Nano 5, 6081 (2011)
  • Kazuo Yamamoto, Charles R. Hogg, Saeki Yamamuro, Tsukasa Hirayama, Sara A. Majetich, Dipolar ferromagnetic phase transition in Fe3O4 nanoparticle arrays observed by Lorentz microscopy and electron holography, Applied Physics Letters 98, 072509 (2011)
  • JitKang Lim, Caitlin Lanni, Eric R. Evarts, Frederick Lanni, Robert D. Tilton, Sara A. Majetich, Magnetophoresis of Nanoparticles, ACS Nano 5, 217 (2011)
  • K. L. Krycka et al., Core-Shell Magnetic Morphology of Structurally Uniform Magnetite Nanoparticles, Physical Review Letters 104, 207203 (2010)
  • Eric R. Evarts, Limin Cao, David S. Ricketts, Nicholas D. Rizzo, James A. Bain, Sara A. Majetich, Spin transfer torque switching of magnetic tunnel junctions using a conductive atomic force microscope, Applied Physics Letters 95, 132510 (2009)
  • Kazuo Yamamoto, Sara A. Majetich, Martha R. McCartney, Madhur Sachan, Saeki Yamamuro, Tsukasa Hirayama, Direct visualization of dipolar ferromagnetic domain structures in Co nanoparticle monolayers by electron holography, Applied Physics Letters 93, 082502 (2008)