Hallmarks of the Kardar-Parisi-Zhang universality class elicited by scanning probe microscopy

Scanning probe microscopy is a fundamental technique for the analysis of surfaces. In the present work, the interface statistics of surfaces scanned with a probe tip is analyzed for both in silico and experimental systems that, in principle, do not belong to the prominent Kardar-Parisi-Zhang universality class. We observe that some features such as height, local roughness and extremal height distributions of scanned surfaces quantitatively agree with the KPZ class with good accuracy. The underlying mechanism behind this artifactual KPZ class is the finite size of the probe tip, which does not permit a full resolution of neither deep valleys nor sloping borders of plateaus. The net result is a scanned profile laterally thicker and higher than the original one implying an excess growth, a major characteristic of the KPZ universality class. Our results are of relevance whenever either the normal or lateral characteristic lengths of the surface are comparable with those of the probe tip. Thus our finds can be relevant, for example, in experiments where sufficiently long growth times cannot be achieved or in mounded surfaces with high aspect ratio.