The specific heat of electron-doped Pr_{ 1.85} Ce_{ 0.15} CuO_4 single crystals is reported for the temperature range 2 - 10 K and magnetic field range 0 - 10 T. A non-linear magnetic field dependence is observed for the field range 0 - 2 T. Our data supports a model with lines of nodes in the gap function of these superconductors. Theoretical calculations of the electronic specific heat for dirty d-wave, clean d-wave, and s-wave symmetries are compared to our data.
Categories: cond-mat.supr-con