SIMES (Stanford Institute for Material and Energy Science)

Physical properties of the electron-doped cuprate showed very small changes when compressed to relatively low pressures, i.e. in the 2-2.5 GPa range. This behavior of the electron-doped cuprates contrast with that of the hole-doped cuprates for which Tc is first substantially enhanced with application of pressure. I present high-pressure diamond-anvil cell (DAC) synchrotron x-ray, resistivity, and ac-susceptibility measurements on the electron-doped HTSc cuprate Pr_2−xCe_xCuO₄ to much higher pressures than previously reported under close to hydrostatic conditions of pressure by using Ne gas as pressure transmitting medium. At 2.72 GPa between 88 and 98% of the superconducting T’ phase of the optimally doped Pr_1.85Ce_0.15CuO₄ transforms into the insulating phase T. With application of pressure, the T phase becomes more insulating. We present here the first example of electron doping in the T structure via pressure. The results have implications for the search for ambipolar high-Tc cuprate superconductors for a unified view of superconductivity in hole- and electron-doped cuprates. For the DAC resistivity measurements we developed a method to “wire” and attach the sample using focused ion beam ultrathin lithography, with the great advantage of using gasses as transmitting pressure media (close to hydrostatic conditions). This method shows promise for resistivity measurements at multi-Mbar pressures.