Single Crystals*

Transition-metal stannides are known to exhibit strong d-p hybridization, leading to narrow - band gap semiconductors. We have successfully grown Ir₃Sn_7-xMn_x single crystals using the flux method. Single crystal x-ray diffraction refinement indicates that Ir₃Sn_7-xMn_x forms a cubic structure (space group Im3m), and the dopant Mn occupies the Sn site. For x = 0.1, the electrical resistivity shows metallic behavior and can be described by ρ = ρ_o + aT² + bT between ~22 K and 300 K. An upturn is observed below 22 K, which is due to an antiferromagnetic (AFM) transition as reflected in the magnetization. Unexpectedly, the application of magnetic field results in negative magnetoresistance below the AFM transition. The effect of Mn doping will be discussed.