Investigation of ferroelectric domains with piezoresponse force microscopy
by
DrElisabeth Sörgel(Physikalisches Inst., Universität Bonn)
→
Europe/Stockholm
FA32
FA32
Description
The increasing number of applications of ferroelectric domain structures causes a strong demand for their reliable visualization.
In the past decade piezoresponse force microscopy (PFM) has become a standard tool for high-resolution imaging of ferroelectric domain patterns. At closer inspection, however, it turned out that the contrast mechanisms of PFM had not yet been understood completely.
Indeed this is mandatory for drawing reliable conclusions from PFM images.
In my talk, I will firstly discuss ferroelectricity and possible applications of ferroelectric domain structures. I will than introduce scanning probe techniques, with special emphasis on the scanning force microscope. Using the latter to investigate ferroelectricity leads to the visualization of ferroelectric domain patterns with piezoresponse force microscopy (PFM). The talk will be focussed on the thorough investigation of the contrast mechanisms in PFM imaging. A two-dimensionally poled LiNbO3 crystal with all surfaces optically polished was used as a standard sample.
Interestingly, all crystal faces showed a pronounced domain contrast.
Careful analysis of the measurements allowed us to unequivocally attribute the observed contrast to (i) the piezomechanical deformation of the sample causing the signals on the domain faces and
(ii) electrostatic forces between tip and surface charges leading to a signal only at the domain boundaries.