Systematic measurements of the resistivity, heat capacity, susceptibility, and Hall coefficient are presented for single-crystal samples of the electron-doped superconductor

Ba {({Fe}_{1 - x} {Co}_{x})}_{2} {As}_{2}

. These data delineate an

x − T

phase diagram in which the single magnetic/structural phase transition that is observed for undoped

{BaFe}_{2} {As}_{2}

at 134 K appears to split into two distinct phase transitions, both of which are rapidly suppressed with increasing Co concentration. Superconductivity emerges for Co concentrations above

x \sim 0.025

and appears to coexist with the broken-symmetry state for an appreciable range of doping up to

x \sim 0.06

. The optimal superconducting transition temperature appears to coincide with the Co concentration at which the magnetic/structural phase transitions are totally suppressed, at least within the resolution provided by the finite-step size between crystals prepared with different doping levels. Superconductivity is observed for a further range of Co concentrations before being completely suppressed for

x \sim 0.18

and above. The form of this

x − T

phase diagram is suggestive of an association between superconductivity and a quantum critical point arising from suppression of the magnetic and/or structural phase transitions.

Publications with shared reference:

0 publications found