Characteristics of the phase transition near 147 K in Sr 3 Ir 4 Sn 13

In order to assess the phase transition nature in Sr3Ir4Sn13, we have carried out the electrical resistivity, Hall coefficient, Seebeck coefficient, thermal conductivity, specific heat, and 119Sn nuclear magnetic resonance (NMR) measurements, mainly focusing on the signatures around the phase transition temperature T*=147 K. The phase transition has been characterized by marked features near T* in all measured physical quantities. In particular, the Hall measurement reveals the abrupt change in both magnitude and sign of the charge carriers below T*, providing strong evidence for the Fermi surface reconstruction associated with this phase transition. Moreover, the NMR observations indicate the presence of the splitting of the resonance lines below T* which could be accounted for by the local distortion of the Sn2 icosahedra within the Pm3̄n phase. The NMR Knight shift analysis further provides microscopic evidence for the reduction in both Sn 5s and Ir 5d electronic states near the Fermi surfaces of Sr3Ir4Sn13. With respect to these observations, it suggests that the strong interplay between electronic and structural instability is responsible for the peculiar phase transition in Sr3Ir4Sn13.