Structural transition and anisotropic properties of single-crystallineSrFe2As2

Platelike single crystals of ${\text{SrFe}}_2{\text{As}}_2$ as large as $3\times 3\times 0.5{\text{mm}}^3$ have been grown out of Sn flux. The ${\text{SrFe}}_2{\text{As}}_2$ single crystals show a structural phase transition from a high-temperature tetragonal phase to a low-temperature orthorhombic phase at $T_o=198\text{K}$, and do not show any sign of superconductivity down to 1.8 K. The structural transition is accompanied by an anomaly in the electrical resistivity, Hall resistivity, specific heat, and the anisotropic magnetic susceptibility. In an intermediate temperature range from 198 to 160 K, single-crystal x-ray diffraction suggests a coexistence of the high-temperature tetragonal and the low-temperature orthorhombic phases.