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Final Activity Report Summary - DW DYNAMICS (Dynamics of domain wall propagation in epitaxial magnetic nanostructures for applications to spintronic devices)

Precise control of magnetisation reversal in patterned magnetic nanostructures is a key parameter for future application in random access memories, hard disk media and, more recently, in magnetic logic devices. In the latter case, it has been demonstrated that magnetic elements may perform logic operations analogously to current microelectronic devices and a very promising scheme based on magnetic Domain wall (DW) propagation in magnetic nanostructures has been proposed. However, the relationship between DW dynamics and the structural and magnetic properties is not well understood.

From a technological point of view, the ultimate aim of this project is the optimization of the DW velocity in a nanostructure and a precise driving of a DW between different positions in a nanocircuit which will be useful to propose nanodevices based on DW propagation capable of storing information or performing as logic gates. In order to reach this aim, it has to be studied from a more fundamental approach how structural factors (roughness, defects) or magnetic parameters help increasing the mobility of a domain wall in a nanostructure or help stabilising it.

In this project, the most important aim for the first 12 months was to develop a time resolved magneto-transport system, based on the extraordinary Hall effect, in order to study the domain wall propagation in magnetic nanostructures. This set-up has already been developed and it is currently in use, agreeing with the work plan presented in the proposal. The measurement temperature ranges from 20 K to 320 K, which allows us to test all the range of interest. Preliminary measurements indicate that the exchange bias adds an extra energy barrier in one of the signs of the applied field. This leads to a difference in the domain wall propagation velocity as a function of the sign of the applied field, which may lead to the development of magnetic diodes.

The second phase of the project, currently in progress, is devoted to determine the parameters that may rise the above indicated diode effect. In this sense, antiferromagnetic layers such as FeMn or PtMn are of the highest interest. Also, structural defects will be introduced in order to study the possibility of increasing the energy barrier.

Reported by

Francisco Pintado Fe, 26
33011 OVIEDO
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