Electrical transport measurements under pressure for BaFe2As2 compounds doped with Co, Cr, or Sn

We investigate the in-plane resistivity of single crystalline samples of Ba(Fe1-xCox)(2)As-2 (x = 0.038, 0.047, 0.074, 0.1 and 0.114), Ba(Fe0.973Cr0.027)(2)As-2 and slightly tin-doped BaFe2As2 under various pressures up to 7.5 GPa, in order to establish temperature-pressure, T(P), phase diagrams and to compare the influence of pressure and doping on superconductivity. At ambient pressure, cobalt doping is known to lead to a decrease in the combined magnetic and structural transition temperature T-0. Likewise, an increase of pressure tends to have the same effect for Ba(Fe1-xCox)(2)As-2 for the various values of x. As was seen in the T(P) phase diagram of BaFe2As2, a superconducting dome is observed for Ba(Fe1-xCox)(2)As-2 samples with the dome shifted to lower temperatures and pressures with increased cobalt doping levels. A very different behaviour is noticed for Ba(Fe0.973Cr0.027)(2)As-2 and the slightly tin-doped BaFe2As2 with the decrease of T-0 being close to linear down to 2 K, and no obvious sign of superconductivity in the pressure range investigated.