Observation of a possible charge-density-wave transition in cubic Ce ₃Co ₄Sn ₁₃

We report an observation of a first-order phase transition in Ce ₃Co ₄Sn ₁₃ by means of the specific heat, electrical resistivity, Seebeck coefficient, and thermal conductivity, as well as 59Co nuclear magnetic resonance (NMR) measurements. The phase transition has been evidenced by marked features near T _o155 K in all measured physical quantities except for magnetic susceptibility. This excludes a magnetic origin for the observed phase transition. In addition, x-ray diffraction results below and above T _o confirm the absence of a structural change, suggesting that the peculiar phase transition is possibly related to an electronic origin and/or electron-lattice coupling such as the formation of a charge density wave (CDW). As a matter of fact, the disappearance of the double-peak feature of 59Co NMR central lines below T _o can be realized as the spatial modulation of the electric field gradient due to incommensurate CDW superlattices. Also, a distinct peak found in the spin-lattice relaxation rate near T _o manifests a phase transition and its feature can be accounted for by the thermally driven normal modes of the CDW. From the NMR analyses, we obtained a consistent picture that the change of electronic structures below T _o is mainly due to the weakening of p-d hybridization. Such an effect could result in possible electron-lattice instability and, thus, the formation of a CDW state in Ce ₃Co ₄Sn ₁₃.