Static magnetization in solid 3He has been measured from 10 mK down to 0.3 mK for various molar volumes V (from 24, 14, to 19.26 cm3/mole). The results for bcc 3HHe show that both the ordering temperature TN and inverse of the maximum magnetization at TN vary in proportion to V16.5±1, that the magnetization in the ordered state is almost constant, and that the magnetization reduced by its maximum value is represented by a universal function of the reduced temperature T/TN. The magnetization in hcp 3He shows that its Weiss constant is very small, possibly less than 30 μK.
The phase separation curve of dilute solution of 4 He in liquid 3 He has been studied using a sensitive dielectric technique and a film-flow-tight valve attached to a cell. The solubility of 4 He at low temperatures was larger than the value expected from the equation proposed by Saam et al.
CW and pulsed NMR experiments on 3 He– 4 He mixture of 6.4 % at 0 bar have been made down to 0.53 mK. The absorption signals obtained by a cw NMR method under the field gradient show the existence of several spin wave modes. These spin wave modes are excited at the same time by an rf pulse. The absorption signals are very different from those of the previous results.
Nuclear magnetic susceptibility and Zeeman-exchange relaxation time T Z X of solid 3 He have been measured by pulsed NMR method using Pomeranchuk cooling technique between 15 mK and 0.97 mK in a static field of about 70 gauss. Magnetic transition to the antiferromagnetic phase was observed at 1.00 mK where the susceptibility decreased to 42% of its maximum value. This drop in susceptibility coincides with the abrupt leveling of 3 He pressure in cooling process which shows thermodynamically a phase transition due to abrupt decrease of solid 3 He entropy. The magnitude of T Z X is consistent with the one estimated from BPP (Bloembergen-Purcell-Pound) theory, but the observed temperature dependence can not be explained on this basis.
Heat transfer characteristics from a flat smooth copper surface to liquid 3He have been measured from 0.5 to 1K under saturated vapor pressure. The temperature difference between the copper surface and liquid 3He was measured as a function of heat flux in a thermal equilibrium state. Kapitza thermal resistance was also measured, and the relation between the temperature difference subtracted Kapitza thermal resistance and the heat flux was decided. In the nonboiling state, the observed data agreed with the equation deduced from the convection flow. However, the data were not explained with Kutateladze's correlation in the nucleate boiling state. In the film boiling state, the data agreed with Breen and Westweater's correlation. While the heat flux was increased, a discontinuous decrease of the temperature difference was observed at the transition from the nonboiling state to the nucleate boiling state. While the heat flux was decreased, the temperature difference changed continuously at the transition from the nucleate boiling state to the nonboiling state from 0.8 to 1K, whereas the change was discontinuous below 0.7K. The observed nucleate boiling state was subdivided into three regions by its behavior. A boiling model is considered in order to explain the behavior qualitatively.
It has been known since systematic study by Berman et al that dilute alloy of Au containing small amount of Fe is an excellent material for low-temperature thermocouples, but so far there was no Au(Fe) wires made in Japan commercially. Recently Osaka Oxygen Ind. Ltd. has developed Au+0.07at%Fe wires. This paper describes the tested results on Au(Fe)-Chromel and Au(Fe)-Cu thermocouples from room temperature down to 1.5K. Temperature variation of thermoelectric power and sensitivity, influence of magnetic field on the thermoelectric power, reproducibility and difference among thermoelectric powers of several specimens are examined. And also temperature variation of electrical resistivity of an Au(Fe) wire is determined to calculate its thermal conductivity.
