A team of researchers from ICMAB has proved that unconventional AFM probes are suitable for acquiring a true piezoelectric signal in piezoresponse force microscopy. The work, titled "Diminish electrostatic in piezoresponse force microscopy through longer or ultra-stiff tips," is published in Applied Surface Science.
Piezoresponse force microscopy is a technique used in piezoelectrics. Each year, almost 300 manuscripts included this technique in their research, and the piezoelectric community publishes more than 5000 papers yearly.
In this work, researchers tested nearly every single AFM conductive probe available on the market using a novel method that quantifies the electrostatic contribution in their measurements. The method relies on solving the correlation function that describes the mathematical operations that a lock-in amplifier performs to acquire the signals. After the theoretical description, the same sample is studied with AFM tips available commercially, through the use of two distinct type of tests.
In the first test, the researchers incremented the piezoelectric signal while maintaining a constant electrostatic contribution. By doing this, the mount of the piezoelectric signal increases, and hence, the changes in the final results are dramatically different. From this test, it is found that longer tips provide the cleaner signal from the overall set of probes used. These results are confirmed through the use of independent experiments that corroborates the first results. The implementation of this solution can be used by any AFM manufacturer.
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A. Gomez et al. Diminish electrostatic in piezoresponse force microscopy through longer or ultra-stiff tips, Applied Surface Science (2018). DOI: 10.1016/j.apsusc.2018.01.080