Program Highlights

Magnetic Domain Structure of Cobalt Nanospirals

Eva Schubert, Daniel Schmidt, and Ralph Skomski
Nebraska MRSEC

Charudatta Phatak and Amanda Petford-Long
Argonne National Laboratory

Nanoscale three-dimensional (3D) structures are building blocks for the fabrication of miniature switching devices and can be used as functional units in nanorobotics. The functionality of the 3D structures is affected by their size and shape and may significantly differ depending on the properties of the bulk material. Nebraska MRSEC researchers use deposition under oblique angles of incidence to produce manifold ensembles of magnetic 3D nanostructures with different shapes and sizes, such as cobalt nanospirals shown in the figure.  Collaboration with researchers from Argonne National Laboratory allowed visualizing the magnetic domain structure of individual nanospirals, using Lorentz transmission electron microscopy. The magnetic behavior was found to be of single domain character along the spiral wire, with strong magnetic coupling among the nanospirals due to an alternating direction of magnetization given by the spatial geometry, and the close packed arrangement of the nanomagnets within an array. The findings were recently published in Nano Letters, present the first observation of the complex magnetic domain structure in 3D chiral nanoobjects, and are important for tailoring nanomagnets towards their desired properties. 

These programs are supported by the National Science Foundation, Division of Materials Research, Materials Research Science and Engineering Program, Grant 0820521.

Magnetization map of a cobalt nanospiral (left) showing variations in the magnetization direction (right).