Lattice distortion associated with Fermi-surface reconstruction in Sr3Rh4Sn13

Superconducting Sr3Rh4Sn13 has been of current interest due to indications of a characteristic phase transition associated with structural distortions in its normal state. To further shed light on the nature of the phase transition, we performed a detailed study of single crystalline Sr3Rh4Sn13 by means of the thermal expansion, electrical resistivity, Hall coefficient, Seebeck coefficient, thermal conductivity, as well as Sn119 nuclear magnetic resonance (NMR) measurements, mainly focusing on the signatures around the phase transition temperature T∗=137 K. The phase transition has been characterized by marked features near T∗ in all measured physical quantities. In particular, the NMR characteristics provide microscopic evidence for the reduction in the electronic Fermi-level density of states (DOSs) below T∗. Based on the analysis of the Sn119 NMR spin-lattice relaxation rate, we clearly demonstrated that the Sn 5s partial Fermi-level DOS in Sr3Rh4Sn13 is reduced by 13% across the phase transition. In this respect, it points to the strong association between electronic and structural instability for the peculiar phase transition in Sr3Rh4Sn13.