Nanotribology and nanomechanics of AFM probe-based data recording technology

Abstract

With the advent of scanning probe microscopes, probe-based datarecording technologies are being developed for ultrahigh areal densityrecording, where the probe tip is expected to be scanned at velocities up to100 mm s−1. In one technique, a conductive atomic force microscope (AFM) tip is scanned over a phasechange chalcogenide medium and phase change is accomplished by applying either ahigh or low magnitude of current which heats the interface. Another technique isferroelectric data storage, where a conducting AFM tip is scanned over a leadzirconate titanate (PZT) film, a ferroelectric material. Ferroelectric domains can bepolarized by applying short voltage pulses between the AFM tip and the bottomelectrode layer that exceed the coercive field of the PZT film, resulting in nonvolatilechanges in the electronic properties. Tip wear is a serious concern in both datastorage methods. The understanding and improvement of tip wear, particularly atthe high velocities needed and at high interface temperatures for high data raterecording, is critical to the commercialization of these data storage technologies.This paper presents a review of nanotribological and nanomechanical studieson the materials used in phase change and ferroelectric probe-based recording.Although this work is aimed at probe-based data recording, it is also relevantto the development of robust AFM probes and to the study of nanocontacts ingeneral.