Procedure for Magnetizing a Sample

The purpose of this procedure is to set the magnetization direction of the sample.

1. The sample was placed, according to the procedure in appendix A.1, in a position that had previously been determined, by visual inspection, to allow an electromagnet consisting of a pair of Helmholtz coils to be raised, so that the sample was at its centre, without placing damaging stresses on the sample or surrounding apparatus (section 4.1.)
2. The electromagnet was raised, so that the sample was at its centre.
3. A current of $(4.5\pm{}0.04)\,\mathrm{A}$, equivalent [37] to a field of $(17.9\pm{}0.16)\,\mathrm{kA}\,\mathrm{m}^{-1}$, was passed through the electromagnet for $(10\pm{}2)\,\mathrm{s}$. The sign of the current was chosen to obtain the required direction (up or down) of the magnetic flux density.
4. The electromagnet was lowered away from the sample.