Profound Effect of a Magnetic Field on the Phase Diagram of SuperfluidHe3

Abstract

In the presence of a magnetic field the 3 He A phase is interposed between the normal liquid and the 3 He B phase for all pressures measured, including pressures below that of the polycritical point. This can be understood on the basis of known nuclear paramagnetic properties if at a given pressure both 3 He A and 3 He B have the same critical temperature and if there are plausible small differences in the heat capacties of the two phases.We have discovered that a rather weak magnetic field acting on the weak nuclear paramagnetism of 3 He has a profound effect on the Tj^ line separating 3 He A and 3 He B in the phase diagram of the superfluid. As shown in Fig. 1 for a field of 378 G, the field produces its largest effect in the vicinity of the pressure of the polycritical point (PCP) but it also acts to interpose the 3 He A phase between the normal liquid and 3 He B down to our lowest pressure of less than 8 bars. Both this remarkable effect and the lowfield T AB line may be quantitatively understood on the basis of the known magnetic properties of 1.9 2.0 2.1 2.2 2.3 2.4 2.5 2.6 T-mK FIG. 1. Phase diagram of liquid 3 He in a field of 378 G using the provisional temperature scale of Ref. 4. The low-field T^ line found in Ref. 3 is shown for reference. The PCP occurs at about 21.5 bars.each of the phases if one assumes that both 3 He A and 3 He B have the same pressure-dependent critical temperature and that there is a particularly simple form for the small thermal differences between the two phases. We believe that this result will be important in determining the nature and the relationship of the A and B phases. In particular, in a context of BCS-like pairing theories of the superfluidity, the results suggest that both 3 He A and 3 He B represent triplet states in the same I manifold. 1 The effect of a magnetic field on the A and B features of the pressurization curve has been reported by Gully et al., 2 who find a small splitting of the A feature and a substantial depression of the B feature by a magnetic field. The dependence of the transition temperature T AB from 3 He B to 3 He A on pressure was determined by Paulson, Johnson, and Wheatley 3 by measurements of the magnetization discontinuity in the JB-A transition in a field of 49 G. The present measurements were also made using static nuclear magnetization measurements. The experimental method, apparatus, calibration technique, and accuracy are the same as those described briefly in Ref. 3. The precision of measurement is, however, substantially improved at higher fields, partly because of increased sensitivity but mostly as a result of the reduced magnetometer background, which is thus principally a manifestation of weak electronic magnetism. Furthermore, the transition A* B reported here in 378-and 480-G fields is reversible in the sense that by careful manipulation of temperature [via adjustments in the magnetic field applied to the main cerium magnesium nitrate (CMN)J this transition could be partly effected, then reversed. Once the transition on coolin...

Properties of melting 3He: Specific heat, entropy, latent heat, and temperature

“…9. If V0 is the liquid 3He sample volume on reaching the melting curve, then the number of moles of 3He in the cell was n3 = VolOt (5) where vt = 25.62111 + (33.662-P0)xd cm3/mole…”

“…1-3 In this paper we give a complete description of this work with particular emphasis on experimental detail. 5 Their work, combined with that of Ahonen et al, 6 establishes the phase diagram at pressure less than 34 bar. The P = 0 value of Tc is attributable to Ahonen et al 6 The effect upon TAB of a 378-Oe magnetic field is shown by the 9 5 9 . dashed hne.…”

The paramagnon model and some properties of superfluid 3He

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3He-Two Superfluid Phases

“…Both these measurements were done on the melting curve. Paul son, Kojima, and Wheatley (10) found that in a field of 30 -4 0 mT (300 -400 gauss) a narrow tail of the A-phase extends between the normal Fermiliquid and the B-phase down to 10 bar at least.…”

“…In this paper I shall first describe several experimental facts about liquid (6) (7) (10). Note the logarithmic temperature scale.…”