Double-phase transition and giant positive magnetoresistance in the quasi-skutterudite Gd₃Ir₄Sn₁₃

The magnetic, thermodynamic, and electrical/thermal transport properties of the caged-structure quasi-skutterudite Gd₃Ir₄Sn₁₃ are re-investigated. The magnetization M(T), the specific heat C p (T), and the resistivity ρ (T) reveal a double-phase transition - at T_N1 ∼ 10 K and at T_N2 ∼ 8.8 K - which was not observed in the previous report on this compound. The antiferromagnetic transition is also visible in the thermal transport data, thereby suggesting a close connection between the electronic and lattice degrees of freedom in this Sn-based quasi-skutterudite. The temperature dependence of ρ (T) is analyzed in terms of a power-law for resistivity pertinent to Fermi liquid picture. Giant, positive magnetoresistance (MR) ≈ 80% is observed in Gd₃Ir₄Sn₁₃ at 2 K with the application of 9 T. The giant MR and the double magnetic transition can be attributed to the quasi-cages and layered antiferromagnetic structure of Gd₃Ir₄Sn₁₃ vulnerable to structural distortions and/or dipolar or spin-reorientation effects. The giant value of MR observed in this class of 3:4:13 type alloys, especially in a Gd-compound, is the highlight of this work.