Synthesis and properties of CaFe2As2 single crystals

We report the synthesis and basic physical properties of single crystals of CaFe(2)As(2), a compound isostructural to BaFe(2)As(2) which has been recently doped to produce superconductivity. CaFe(2)As(2) crystallizes in the ThCr(2)Si(2) structure with lattice parameters a = 3.887(4) angstrom and c = 11.758(23) angstrom. Magnetic susceptibility, resistivity, and heat capacity all show a first order phase transition at T(0) = 171 K. The magnetic susceptibility is nearly isotropic from 2 to 350 K. The heat capacity data gives a Sommerfeld coefficient of 8.2 +/- 0.3 mJ mol(-1) K(-2), and does not reveal any evidence for the presence of high frequency (> 300 K) optical phonon modes. The Hall coefficient is negative below the transition, indicating dominant n-type carriers.