Physical and magnetic properties ofBa(Fe1−xRux)2As2single crystals

Single crystals of $\text{Ba}{({\text{Fe}}_{1\ensuremath{-}x}{\text{Ru}}_{x})}_{2}{\text{As}}_{2}$, $xl0.37$, have been grown and characterized by structural, magnetic, and transport measurements. These measurements show that the structural/magnetic phase transition found in pure ${\text{BaFe}}_{2}{\text{As}}_{2}$ at 134 K is suppressed monotonically by Ru doping but, unlike doping with $TM=\text{Co}$, Ni, Cu, Rh, or Pd, the coupled transition seen in the parent compound does not detectably split into two separate ones. Superconductivity is stabilized at low temperatures for $xg0.2$ and continues through the highest doping levels we report. The superconducting region is domelike, with maximum ${T}_{c}(\ensuremath{\sim}16.5\text{ }\text{K})$ found around $x\ensuremath{\sim}0.29$. A phase diagram of temperature versus doping, based on electrical transport and magnetization measurements, has been constructed and compared to those of the $\text{Ba}{({\text{Fe}}_{1\ensuremath{-}x}T{M}_{x})}_{2}{\text{As}}_{2}$ ($TM=\text{Co}$, Ni, Rh, and Pd) series as well as to the temperature-pressure phase diagram for pure ${\text{BaFe}}_{2}{\text{As}}_{2}$. Suppression of the structural/magnetic phase transition as well as the appearance of superconductivity is much more gradual in Ru doping, as compared to Co, Ni, Rh, and Pd doping, and appears to have more in common with ${\text{BaFe}}_{2}{\text{As}}_{2}$ tuned with pressure; by plotting ${T}_{S}/{T}_{m}$ and ${T}_{c}$ as a function of changes in unit-cell dimensions, we find that changes in the $c/a$ ratio, rather than changes in $c$, $a$, or $V$, unify the $T(p)$ and $T(x)$ phase diagrams for ${\text{BaFe}}_{2}{\text{As}}_{2}$ and $\text{Ba}{({\text{Fe}}_{1\ensuremath{-}x}{\text{Ru}}_{x})}_{2}{\text{As}}_{2}$, respectively.