Uniaxial Alignment of the Smallest Diamagnetic Susceptibility Axis Using Time-Dependent Magnetic Fields

A diamagnetic particle with magnetic susceptibilities χ3 < χ2 = χ1 < 0 was subjected to a rotating magnetic field to obtain an alignment of the χ3 axis (the smallest susceptibility axis) in the direction perpendicular to the plane of the rotating magnetic field. A polymer short fiber, whose fiber axis coincides with the χ3 axis, was suspended in a fluid with the same density, and then a rotating magnetic field generated by a rotation of a pair of permanent magnets was applied. The fiber axis, rotating following the applied field, finally ended up with an alignment perpendicular to the plane of the rotating magnetic field. The experimental data on the time course of the alignment was in good agreement with the numerical calculation based on the equation of rotation.