We have measured the melting curve of He-4 in the temperature range from 10 to 400 mK with the accuracy of about 0.5 mu bar. Crystals of different quality show the expected T-4 dependence in the range from 80 to 400 mK without any sign of the supersolid transition, and the coefficient is in excellent agreement with available data on the sound velocity in liquid He-4 and on the Debye temperature of solid He-4. Below 80 mK, we have observed a small deviation from T-4 dependence, which, however, cannot be attributed to the supersolid transition, because instead of decrease the entropy of the solid rather remains constant, about 2.5x10(-6) R.
Despite the great current emphasis on possible supersolid behaviour in solid 4He, this work shows that there is no evidence whatsoever for a supersolid transition in the temperature dependence of the melting curve. Tsepelin was responsible for designing and constructing the experimental setup. RAE_import_type : Journal article RAE_uoa_type : Physics
