Multiple charge density waves compete in ternary rare-earth nickel carbides, RNiC2 (R: Y, Dy, Ho, and Er)

Single-crystal x-ray-diffraction experiments and electrical resistivity measurements were performed on intermetallic compounds of formula RNiC2 [rare earth (R): Y, Dy, Ho, and Er]. In the series of diffraction studies, we found three kinds of satellite reflections that had different wave vectors [incommensurate q1ic:(0.5,0.5+η,0) and commensurate q1c:(0.5,0.5,0) and q2c:(0.5,0.5,0.5)] at temperatures where their resistivities show anomalies, such as a hump, a sharp increase, or a dent. Satellite reflections with nearly identical wave vectors have also been reported in RNiC2 composed of earlier lanthanide atoms (GdNiC2 and TbNiC2). These results indicate the formation of a charge density wave (CDW) also in RNiC2 studied in this paper. We found strong competition between the q1ic and the q2c CDWs in DyNiC2 and YNiC2, and that only the q2c CDW existed in HoNiC2 and ErNiC2. Based on the results obtained in the present paper and those of SmNiC2,GdNiC2, and TbNiC2 reported before, we discuss the CDW transitions in the RNiC2 family.