Itinerant antiferromagnetism in BaCr${}_2$As${}_2$

We report single crystal synthesis, specific heat and resistivity measurements and electronic structure calculations for BaCr${}_2$As${}_2$. This material is a metal with itinerant antiferromagnetism, similar to the parent phases of Fe-based high temperature superconductors, but differs in magnetic order. Comparison of bare band structure density of states and the low temperature specific heat implies a mass renormalization of $\sim$ 2. BaCr${}_2$As${}_2$ shows stronger transition metal - pnictogen covalency than the Fe compounds, and in this respect is more similar to BaMn${}_2$As${}_2$. This provides an explanation for the observation that Ni and Co doping is effective in the Fe-based superconductors, but Cr or Mn doping is not.