Unusual charge density wave transition and absence of magnetic ordering in Er2Ir3Si5

The first-order charge density wave (CDW) phase transition of ${\mathrm{Er}}_{2}{\mathrm{Ir}}_{3}{\mathrm{Si}}_{5}$ is characterized by a crystal structure analysis, and electrical resistivity, magnetic susceptibility and specific heat measurements. The incommensurate CDW is accompanied by a strong lattice distortion, from which it is shown that the CDW resides on zigzag chains of iridium atoms. The CDW transition affects the magnitude of the local magnetic moments on ${\mathrm{Er}}^{3+}$, implying strong coupling between CDW and magnetism. This could account for the observation that magnetic order is suppressed down to at least 0.1 K in the high-quality single crystal presently studied. Any disorder in the crystallinity, as in ceramic material, broadens and suppresses the CDW transition, while magnetic order appears at 2.1 K.