Operation of Conventional Vibrating Sample Magnetometer at 3He Temperatures and in High Magnetic Fields

Simple modifications of only the tail section of a conventional vibrating sample magnetometer (VSM) are described which permit magnetic moment measurements at 3He temperatures. The sample is immersed in the liquid 3He for good thermal contact. Tests with a cerous magnesium nitrate sample demonstrate that thermal equilibrium between the sample and the bath is achieved even at the maximum vibration amplitude of our instrument. The modifications can easily be made in relatively small volumes. The 3He section for our system had an inner diameter=0.58 cm, an outer diameter=0.79 cm, and was surrounded by a small 4He Dewar inserted into the pickup coils. The coils fit into a 2.54 cm bore, 60 kG superconducting solenoid. The sensitivity, field range, and other advantages are identical to that of the conventional VSM.