Optomechanical Actuation of Diamagnetically Levitated Pyrolytic Graphite

Abstract

The magnetic susceptibility of pyrolytic graphite (PyG) is temperature dependent. Under an external magnetic field, a levitated PyG sample with a localized temperature change experiences unequal diamagnetic forces. In this paper, we present a study of the macroscale optomechanical displacement of a levitated PyG sample by using a laser source to locally increase the temperature. Dynamic finite-element method simulations show that a localized increase in the sample temperature, simulating a laser source, decreases the diamagnetic force in that local area, leading to the displacement of the PyG sample in the plane of the permanent magnet array. Experimental setups built using different laser sources and samples confirm the range of applicability of the actuation phenomenon to different conditions. An additional setup without moving parts reduced the likelihood by which airflow could have caused the displacement, as we suspect happened in the previous studies.