Magnetic Properties of Liquid 3He below 3 m°K
Features observed along the 3He melting curve in compressional cooling experiments have suggested that at least one and perhaps two phase changes take place in either the solid and/or the liquid 3He within the cell at temperatures below 3 m°K.1 In experiments in which the cell pressure was recorded as a function of time during periods in which the rate of compression dV/dt was held constant, two unexpected features were reproducibly obtained on the resulting pressurization curve which were labeled the A and B transitions, respectively, by Osheroff et al. The A transition is characterized by a sudden decrease in the rate of cell pressurization dP/dt upon cooling by roughly a factor of two in magnitude, all within a pressure interval of less than 3 × 10−4 atm. A nearly equal but opposite change in dP/dt is observed upon warming at precisely the same pressure. The pressure at which the A transition occurs in zero magnetic field is 1.70 × 10−1 atm above the cell pressure at 7 m°K, and P(A) is lowered by the application of magnetic fields by an amount roughly equal to −6.7 × 10−5 H 2 atm/kG2. The pressure P(A) corresponds to a temperature of about 2.7 m°K obtained by extrapolating the shifted melting curve of Johnson et al.1,2 The B transition is characterized by a sudden drop in cell pressure by about 3 × 10−4 atm upon cooling and by a brief hesitation in the cell pressure as it decreases upon warming (B’ transition). The pressure P(B’) is reproducibly 1.89 × 10−1 atm above the cell pressure at 7 m°K in zero magnetic field, and is shifted to higher pressures by the application of magnetic fields by an amount given roughly by ΔP = +2.02 × 10−3 H 2 atm/kG2.
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