Thermomechanical effect in normal liquid super(3)He with non-magnetic boundary scattering

The thermomechanical effect in normal liquid super(3)He, confined in a porous plug pre-plated with 4 super(4)He non-magnetic monolayers, has been measured. A previous experiment showed that there is a thermomechanical effect (analogue of thermoelectricity) but only when the super(3)He is confined in pores with d < < Tl, where d is the pore size and l the bulk super(3)He quasiparticle mean free path. The effect was large, an order of magnitude larger than a theoretical determination by Edwards, Culman and He. This was possibly a magnetic scattering anomaly; we therefore repeated the experiment with the pre-plated porous plug, with dramatically different results. In the d < < Tl limit, below 5 mK, we find dP/dT approximately S/6, compared with the theoretical S/3, where S is the entropy per unit volume.