Nano-magnetism and Magnetic Random Access Memory (MRAM)

The field of nanoelectronics is overwhelmingly dedicated to the exploitation of the behavior of electrons in electric fields. Materials employed are nearly always semiconductor-based, such as Si or GaAs, and other related dielectric and conducting materials. An emerging basis for nanoelectronic systems is that of magnetic materials. In the form of magnetic random access memories (MRAM), nanoscale magnetic structures offer fascinating opportunities for the development of low-power and nonvolatile memory elements. For a good MRAM review check out IBM Journal of Research & Development

One of the challenges facing magnetic data storage technology is how to reduce the size of the individual data storage elements. Replicating Moore's law for magnetic storage has so far been successful - magnetic storage capacity is doubling every two years. There are, however, physical limits to how far the technology can ultimately go. Below some critical size individual grains or particles will reach the superparamagnetic limit and will no longer store information.

One of the ideas that has been proposed to extend the limits of magnetic storage is to use ring-shaped nano-particles in a vortex state. Such particles produce much lower dipolar fringe fields that greatly reduce the interaction with their neighbors, and consequently make the stored information more stable. The vortex state is also intrinsically quite stable especially if formed in a ring-like structure that eliminates the vortex core. If such an application were to evolve it would require the information to be stored in the chirality of the vortex. In this context understanding magnetic domain formation, and controlling the vortex chirality are important issues.

  • Vortices in magnetic nano-rings, by J. Sautner, N. Jahedi and V. Metlushko. Joshua Sautner and Nima Jahedi were Prof.Metlushko's students

    Our program combines sophisticated fabrication, advanced materials, and qualitatively new science occurring in nanoscale structures.

  • This work would not have been possible without the excellent assistance of my colleagues:

  • M. Grimsditch, G. Crabtree, S. D. Bader, V. Novosad, G. P. Felcher, J. Srajer, D. J. Hinks, L. Rehn, M. Kirk, N. Zaluzec, J. Johnson, U. Welp, V. Vlasko-Vlasov, Materials Science Division, Argonne National Laboratory
  • B.Ilic, Cornell University
  • Wenjun Fan, Zhao Zhang, S.R.J.Brueck, University of New Mexico
  • H.Koo, R.D. Gomez, University of Maryland
  • P.Neuzil, R.Kumar, Institute of Microelectronics, Singapore
  • L. DeLong, University of Kentucky
  • M.Roseman, P. Grutter, McGill University, Canada
  • B. Terris, IBM Almaden Research Center
  • M. E. Hawley, Los Alamos National Laboratory
  • V.V. Moshchalkov, Prof.Y. Bruynseraede, K.U. Leuven, Belgium
  • G. Guentherodt, RWTH Aachen, Germany
  • P.Vavassori, University of Ferrara, Italy
  • W. Porod, University Notre Dame
  • Xiaobin Zhu, Seagate
  • P.Vavassori, CIC nanoGUNE, Spain

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