Development of a New Tip Assembly for Lateral Force Microscopy and Its Application to Thin Film Magnetic Media

Abstract

In a Lateral Force Microscope (LFM), appropriate spring constants of the tip assembly are essential for obtaining proper normal loads for wear or scratch tests and good lateral force signals. We developed a new tip assembly design for which the lateral and normal springs can be changed independently. It was installed on a LFM where two optical heads are used to detect the lateral and normal deflections of the tip assembly for simultaneous measurements of the surface topography and friction force. Reliable calibration procedures for the LFM are presented. The LFM was used to measure the lateral forces in wear tests under various normal forces for thin film magnetic disks with and without a carbon overcoat. The friction coefficient is constant in the load range where there is no wear and increases with normal load after the tip starts to damage the surface. The carbon-coated disk has a lower friction coefficient and can support larger normal loads without wear.