Magnetorotation Experiment of Diamagnetic Single-Crystal Grains Suspended in a Gas Medium for Examining Dust Alignment in the Interstellar Region

Abstract

The magnetic alignment of diamagnetic grains suspended in a gas medium is observed for the first time on micron-sized single crystals of graphite by the use of a system newly developed for this purpose. Previously magnetic alignment was studied on grains suspended in a liquid medium. The field of full orientation H s at T =293 K was as small as 140 G when the crystal size was 3.5 µm in diameter and 1.0 µm in thickness. It was examined experimentally that the alignment in the gas medium depends on the balance between the thermal agitation energy and the diamagnetic anisotropy energy induced in the particle. This experiment is necessary in order to examine the grain alignment of the interstellar region, which is the basis to observe the interstellar magnetic field. The experiment is necessary also to determine the diamagnetic anisotropy for various inorganic materials through high-temperature measurements.