Mixed-valence transition inYbInCu4

We present single-crystal data of mixed-valent ${\mathrm{YbInCu}}_4$ including a description of the single-crystal-growth procedure. Many of the data, such as magnetic susceptibility, electrical resistivity, and lattice constant, are similar to previously published polycrystalline data although the mixed-valent transition at 66.9 K is sharper than in the latter case. In addition, elastic-constant data are presented which exhibit a pronounced softening of the bulk modulus and the Poisson ratio at ${\mathit{T}}_{\mathit{a}}$.