Strongly coupled charge-density wave transition in single-crystal Lu5Ir4Si10

We report the observation of a strongly coupled first-order charge-density wave (CDW) transition in a high-quality single crystal of the intermetallic compound Lu5Ir4Si10. The first-order nature is ascertained by a very narrow and huge cusp (360 J/mol K) in the specific heat. The susceptibility and the resistivity also show sharp jumps at the transition T-CDW=83 K. The periodic lattice distortion associated with the CDW is exemplified by the formation of x-ray superlattice reflections along the tetragonal (c) over right arrow axis with (q) over right arrow approximate to(0,0,3/7) (T <83 K). Although our results are in accordance with a quasi-one-dimensional CDW scenario, the first-order transition suggests a strong interchain coupling. We propose Lu5Ir4Si10 as a paradigm of such strong-coupling CDW systems. [S0163-1829(99)05808-7].