Development of pressure cell for specific heat measurement at low temperature and high Magnetic field

We report the performance of Ag–Pd–Cu alloy as the material of a pressure cell to carry out specific heat measurements at low temperatures and high magnetic fields. The Ag–Pd–Cu alloy is advantageous to reduce the background due to the nuclear specific heat in the pressure cell growing at low temperatures and high magnetic fields. We prepared 70-20-10 alloy composed of $70mass%$ of Ag, $20mass%$ of Pd, and $10mass%$ of Cu. The maximum hardness over 100 HRB (Rockwell-B scale) is achieved by the heat treatment. The magnetization and susceptibility results show that the alloy includes a small amount of magnetic ions, whose concentration is smaller than that in the Be–Cu alloy. We confirm that the specific heat of a piston cylinder cell made of the 70-20-10 alloy increases smoothly from 0.2 to 9 K and the nuclear specific heat decreases drastically in magnetic field compared to that expected in the Be–Cu alloy. The pressure value in the cell at low temperature increases almost linearly up to $P=0.4GPa$⁠, which is nearly the limit of the inner piston made of the 70-20-10 alloy, with increasing of the load applied at room temperature.