Magnetic Moment and Susceptibility of MnCl2 as a Function of Field along the b Magnetic Axis to 95 kG from 1.3° to 4.2°K

Values of magnetic moment, isothermal differential susceptibility, magnetic work and free energy change of single‐crystal MnCl₂ have been obtained by means of a digital voltmeter integrating the dc potential on a sensing coil surrounding a spherical sample. This substance becomes antiferromagnetic near 2°K. The sample was moved vertically along the measuring coil axis which coincided with the field direction in an accurately stabilized field in a long solenoid. The observations cover the range from 1.3° to 4.2°K and fields to 95 kG. The measurements show no signs of irreversibility over the above region. The sample was high purity anhydrous MnCl₂ with its b magnetic axis (a crystallographic axis) parallel to the field. The saturation value of MnCl₂ was found to be 27 988 G·cm³/mole corresponding to a g=2.004 for a ⁶S${}_{\frac{5}{2}}$ state. Problems connected with the accurate use of digital integrators for such measurements are discussed and illustrated by means of various experiments. Magnetic effects due to air, should leaks occur into a refrigerant under vacuum within a solenoid, are discussed and a method of removing solid air from the region near the magnetic sample during magnetic measurements is suggested.