Abstract
For thin film studies in magnetic surface and size effects, magnetometers of extreme sensitivity are required, capable to detect a small part of one monolayer. They may be realized as torsion magnetometers using the torque on an anisotropic film in a homogeneous field. A complete analysis of the method is given for ferromagnetic films, both saturated and unsaturated, and for paramagnetic (superparamagnetic) films. Two existing instruments are described, both working in a contact gas, from 4 to 600 K. The first one works in the oscillation mode, using the period of oscillation of the oscillating film as a measure of the magnetic directional moment; this instrument is capable to detect 2·10−18 Wb·m (2·10−9 G·cm3). The second one works preferentially in the static mode, as a loop tracer, in which the magnetic torque is compensated by a quadrant electrometer; this second instrument detects 6·10−18 Wb·m in the static mode; with a reduced sensitivity (2·10−16 Wb·m), it works also in the oscillation mode. The relative merits of both instruments are discussed.
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Gradmann, U., Kümmerle, W. & Tham, R. High sensitivity torsion magnetometers for oligatomic films. Appl. Phys. 10, 219–225 (1976). https://doi.org/10.1007/BF00897219
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DOI: https://doi.org/10.1007/BF00897219