Nuclear susceptibility of liquid He3—I

An accurate study of the nuclear molar susceptibility of liquid He³ has been made. Particularly emphasized was the comparison of in the liquid with that in solid He³. The experimental results of this work define a three-dimensional surface T/C versus temperatureT and molar volumeV between 0.35 and 2.2° K and between 26 and 37 cm³/mole. HereC is the molar Curie constant of solid He³, assumed to beN_Aµ²/k_BT, where is the nuclear magnetic moment and N_A Avogadro's number. The measurements were accomplished using a carefully designed pulsed NMR set, and sample-and-hold circuitry with a digital voltmeter for readout. Most of the measurements were made at fixed temperature relative to a sample of bcc solid He³, usually at a density of 22.50 cm³/mole. These data were complemented by measurement of versusT at fixed pressure. Except at the highest temperatures, the scatter in the values was about 0.3%, and the results are estimated to be accurate within ±0.5%. At sufficiently high temperatures, the susceptibility is found to tend asymptotically towards Curie's law by comparison with solid He³. The deviation from Curie's law, to temperatures near 0.5° K, could be empirically written as (1–T/C)=bT^dwhereb andd are density-dependent parameters. Comparison with theories and previous measurements of the nuclear susceptibility are made. Below 1° K, the present results are about midway between those of Beal and Hatton⁹ and those of Thomson, Meyer, and Adams.⁸Research supported by a grant from the National Science Foundation and from the AROD. The results have been presented as an Abstract inBull. Am. Phys. Soc.14, 601 (1969), submitted in partial fulfillment for the Ph.D. in physics by J. R. Thompson, May 1969.