Enhancement of the Superconducting Transition Temperature under Pressure   in Rare-Earth Doped Ca$_{1-x}$La$_x$Fe$_2$As$_2$ (x=0.27)
  We report measurements of the pressure dependence of the superconducting transition temperature T_c in single crystal samples of the rare-earth doped superconductor Ca$_{0.73}$La$_{0.27}$Fe$_2$As$_2$. We track T_c with two techniques, via in-plane resistivity measurements and with a resonant tunnel diode oscillator circuit which is sensitive to the skin depth. We show that initially T_c rises steeply with pressure, forming a superconducting dome with a maximum T_c of ~44 K at 20 kbar. We discuss this observation in the context of other electron-doped iron pnictide superconductors, and conclude that the application of pressure offers an independent way to tune T_c in this system. 
Swee K. Goh, Lina E. Klintberg, J. M. Silver, F. M. Grosche, S. R.   Saha, T. Drye, J. Paglione, Mike Sutherland
cond-mat.supr-con cond-mat.str-el