Effect of pressure on the superconducting critical temperature of   La[O_{0.89}F_{0.11}]FeAs and Ce[O_{0.88}F_{0.12}]FeAs
  We have performed several high-pressure resistivity experiments on the recently discovered superconductors La[O_{0.89}F_{0.11}]FeAs and Ce[O_{0.88}F_{0.12}]FeAs. At ambient pressure, these materials have superconducting onset temperatures T_c of 28 K and 44 K, respectively. While the T_c of La[O_{0.89}F_{0.11}]FeAs goes through a maximum between 10-68 kbar, in qualitative agreement with a recent report by Takahashi et al., the T_c of Ce[O_{0.88}F_{0.12}]FeAs decreases monotonically over the measured pressure range. At 265 kbar, the T_c of the cerium-based compound has been suppressed below 1.1 K. 
D. A. Zocco, J. J. Hamlin, R. E. Baumbach, M. B. Maple, M. A. McGuire,   A. S. Sefat, B. C. Sales, R. Jin, D. Mandrus, J. R....