Pressure study of solid 3He through the nuclear ordering temperature

The pressure of solid 3He has been measured as a function of temperature, T, down to and through its nuclear ordering temperature for molar volumes from 24.19 to 23.72 cm3. The pressure measurement above the ordering temperature reveals that besides the 1/T term there are a significant negative term in 1/T2 and a positive term of 1/T3. A discontinuous change in pressure which was associated with the first kind phase transition was observed through the ordering temperature. The molar volume dependences of the ordering temperature, the pressure coefficients and the discontinuous change in pressure are discussed in terms of the exchange interactions. (orig.)