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.
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. Grütter, 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. Güntherodt, RWTH Aachen, Germany
P.Vavassori, University of Ferrara, Italy
W. Porod, University Notre Dame
Xiaobin Zhu, University of Alberta, Canada
P.Vavassori, University of Ferrara, Italy
Quick Access to Several of Our Recent Publications
- Physical
Review B 69, 214404 (2004) - Magnetization reversal via single and double
vortex states in submicron Permalloy ellipses
- Applied
Physics Letters, Vol. 82, No. 21, pp. 3716–3718 (2003) -Shape effect on
magnetization reversal in chains of interacting ferromagnetic elements
- Journal
of Applied Physics, Volume 93, Issue 10, pp. 7059-7061 (2003) -Control of
domain patterns in square shaped nickel rings
- Applied
Physics Letters, Vol. 82, No. 6, pp. 982–984 (2003) - Characterization of
the nanostructures of a lithographically patterned dot array by x-ray
pseudo-Kossel lines
- Applied
Physics Letters, Vol. 82, No. 1, pp. 82–84 (2003) - Polarized neutron
scattering from ordered magnetic domains on a mesoscopic permalloy antidot
array
- Journal
of Applied Physics, Vol. 93, No. 10, pp. 8540–8542 (2003) -Construction of
hysteresis loops of single domain elements and coupled permalloy ring arrays
by magnetic force microscopy
- Journal
of Applied Physics, Vol. 93, No. 10, pp. 8418–8420, (2003) - In-plane and
out-of-plane uniaxial anisotropies in rectangular arrays of circular dots
studied by ferromagnetic resonance .
- Physical
Review B, 68, 054408 (2003) -Magnetization reversal in arrays of Co rings
- Physical
Review B, 67, 134429 (2003) - Metastable states during magnetization
reversal in square permalloy rings
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.
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:
Quick Access to Several of Our Recent Publications
- Physical Review B 69, 214404 (2004) - Magnetization reversal via single and double vortex states in submicron Permalloy ellipses
- Applied Physics Letters, Vol. 82, No. 21, pp. 3716–3718 (2003) -Shape effect on magnetization reversal in chains of interacting ferromagnetic elements
- Journal of Applied Physics, Volume 93, Issue 10, pp. 7059-7061 (2003) -Control of domain patterns in square shaped nickel rings
- Applied Physics Letters, Vol. 82, No. 6, pp. 982–984 (2003) - Characterization of the nanostructures of a lithographically patterned dot array by x-ray pseudo-Kossel lines
- Applied Physics Letters, Vol. 82, No. 1, pp. 82–84 (2003) - Polarized neutron scattering from ordered magnetic domains on a mesoscopic permalloy antidot array
- Journal of Applied Physics, Vol. 93, No. 10, pp. 8540–8542 (2003) -Construction of hysteresis loops of single domain elements and coupled permalloy ring arrays by magnetic force microscopy
- Journal of Applied Physics, Vol. 93, No. 10, pp. 8418–8420, (2003) - In-plane and out-of-plane uniaxial anisotropies in rectangular arrays of circular dots studied by ferromagnetic resonance .
- Physical Review B, 68, 054408 (2003) -Magnetization reversal in arrays of Co rings
- Physical Review B, 67, 134429 (2003) - Metastable states during magnetization reversal in square permalloy rings