A simple magnetometer for planar geometries

A laboratory technique based on the elementary principle of the angular pendulum has been adapted to measuring magnetization and anisotropy fields of planar samples. A frictionless gas bearing serves as the sample mount and provides a moment of inertia large enough to permit samples of sizeable magnetic moments to oscillate in kilogauss fields with periods large enough to be measured with a simple stopwatch. This method is shown to be suitable for magnetic oxides where eddy-current damping does not occur, and particularly for epitaxial films and grain-oriented sintered specimens where magnetocrystalline anisotropy can also be determined. Experimental results for magnetization are in good agreement with accepted values and anisotropy measurements conform to expected results for garnet epitaxial films and an oriented barium ferrite sample. Applications to recording tape are also demonstrated.