Magnetic characterization of single nanostructures
https://dipc.ehu.eus/en/scientific-activities/joint-seminar-agenda/cic-nanogune/seminar112
https://dipc.ehu.eus/@@site-logo/dipc-logo.png
Magnetic characterization of single nanostructures
CIC nanoGUNE Seminars
- Speaker
-
Hans Peter Oepen. University of Hamburg, Hamburg, Germany
- When
-
2010/11/22
12:00
- Place
- nanoGUNE seminar room, Tolosa Hiribidea 76, Donostia - San Sebastian
- Add to calendar
-
iCal
Subscribe to Newsletter

In this talk new approaches are presented to study the magnetic behavior of
single nanostructures and the interaction between nanostructures. In principal
a micro- or nanoscaled device is built that gives access to the magnetic
properties of individual nanostructures. To quantify the interaction between
nanostructures exhibiting flux closure domain pattern we have developed a new
technique to study the magnetization behavior in single elements. Utilizing a
highly focused ion beam (FIB) we create structures in a thin film including
electrical contacts, which allows to measuring the energy state of the
individual element via the anisotropic magnetoresistance. The sizes of the
magnetic Py structures vary between 300 x 600 nm2 and 500 x 1000nm2. The
energy of the magnetic ground state is measured via the reversal magnetization
behavior on applying a magnetic field along the short axis of the rectangles.
When identical elements are positioned next to the rectangle the magnetization
behavior changes depending on the separation between the structures. This is
used to quantify the interaction between the elements.
To fabricate smaller structures with diameters below 20 nm we use low energy
ion milling to structure thin films or multilayers. For that purpose we
deposit nanosized particles on Co/Pt multilayers. The particles protect the
magnetic multilayers locally from being removed by ions while between the
particles the magnetic multilayer is erased. On applying the correct dose an
array of magnetic multilayer dots is created. The anisotropy and the total
amount of magnetic material per nanodot can be purposely tuned so that the
magnetic property of the dots can be varied from ferromagnetic to
superparamagnetic behavior. The magnetization behavior of the dots is
determined utilizing the Anomalous Hall Effect (AHE). To attain a Hall voltage
crosses are fabricated by lithographical methods on which the multilayer is
deposited. Performing the above mentioned procedures of transferring the
nanoscale structure into the film we generate Hall geometries that contain
only very small amounts of nanoparticles. Up to now we were able to measure
the magnetic behavior of ensemble with a minimal number of about 18 nanodots.
Based on our experience we estimate that the technique has the potential for
the investigation of single nanodots magnetization behavior.