Mn-induced spin glass behavior in metallic Ir₃Sn_7−xMn_x

Transition metal stannides are usually semiconductors with a narrow band gap. We report experimental investigation on metallic Ir₃Sn_7–xMn_x (x = 0 and 0.56). Single crystal x-ray diffraction refinement indicates that Ir₃Sn_7–xMn_x crystals form a cubic structure (space group Im^¯3m) with the lattice parameter a = 9.362(4) Å for x = 0 and 9.328(6) Å for x = 0.56. The electrical resistivity shows metallic behavior between 2 K and 300 K with T² dependence at T < 30 K for x = 0, reflecting the Fermi-liquid ground state. While Ir₃Sn₇ exhibits weak diamagnetism, partial substitution of Sn by Mn results in spin glass behavior in Ir₃Sn_7−xMn_x below T_g ∼ 13 K for x = 0.56. Remarkably, an upturn in the resistivity is observed in x = 0.56 below ∼2T_g, suggesting strong spin fluctuation. This fluctuation is suppressed by the application of magnetic field, which is reflected in the observation of negative magnetoresistance. The unusual properties that emerge due to Mn doping are discussed.