Transport measurements at low temperatures in a diamond anvil cell with helium as pressure medium

We report the development of a technique to measure transport properties using a new diamond anvil cell and helium as pressure transmitting medium to ensure hydrostatic conditions. The chamber pressure is measured at any working temperature below 300 K by the ruby fluorescence method. This technique has been used to pressures up to 3 GPa at T=5 K to measure the effect of hydrostatic pressure and magnetic field on the superconducting transition temperature of a single crystal of the anisotropic cuprate superconductor Bi2.1Sr1.9−yLayCuO6+δ.