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Research Highlight

Quantifying Nanoscale Hysteresis Measurements

Artifacts in traditional AFM detection schemes can lead to false claims of ferroelectric or ionic hysteresis. Interferometric detection is used to separate cantilever and tip motions allowing unambiguous and quantitative mapping of electromechanical phenomena. Almonds, which are known not to be ferroelectrics, show artificial hysteresis when only cantilever motion is examined.

Scientific Achievement

A fully quantitative and artifact free approach for nanoscale mapping of electromechanics is achieved by combining interferometric sensing with voltage modulated atomic force microscopy (AFM).

Significance and Impact

Reliable quantification of electromechanical responses can avoid mistaken identification and is critical to diverse applications from information technologies to polymer and biological sensors.

Research Details

– Cantilever motion in traditional AFM can mask local properties and lead to false claims of ferroelectric switching or ionic motion.
– Hysteresis in cantilever motion is almost universal, but in many cases (e.g. the almond nut) is an artifact of the AFM measurement scheme not a property of the material.
– Interferometric sensing measures tip motion leading to an artifact free and quantitative method for nanoscale functional mapping.
Liam Collins, Yongtao Liu, Olga S. Ovchinnikova, and Roger Proksch, "Quantitative Electromechanical Atomic Force Microscopy," ACS Nano 13 (7), 8055-8066 (2019).  DOI: 10.1021/acsnano.9b02883