Tunneling Spectroscopy Of Al/Alox/Pb Subjected To Hydrostatic Pressure

We develop an experimental tool to investigate high-pressure electronic density of state by combining electron tunneling spectroscopy measurements with high-pressure technique. It is demonstrated that tunneling spectroscopy measurement on Al/AlOx/Pb junction is systematically subjected to hydrostatic pressure up to 2.2 GPa. Under such high pressure, the normal state junction resistance is sensitive to the applied pressure, reflecting the variation of band structure of the barrier material upon pressures. In superconducting state, the pressure dependence of the energy gap Delta(0), the gap ratio 2 Delta(0)/k(B)T(c), and the phonon spectral energy is extracted and compared with those obtained in the limited pressure range. Our experimental results show the accessibility and validity of high pressure tunneling spectroscopy, offering wealthy information about high pressure superconductivity. (C) 2015 AIP Publishing LLC.