The low-temperature heat capacity of superconducting ternary iron silicides ${\mathrm{Lu}}_2$${\mathrm{Fe}}_3$${\mathrm{Si}}_5$, ${\mathrm{Sc}}_2$${\mathrm{Fe}}_3$${\mathrm{Si}}_5$, and ${\mathrm{Y}}_2$${\mathrm{Fe}}_3$${\mathrm{Si}}_5$ has been measured, revealing several anomalous properties of the superconducting state of these materials. These materials show a large linear term in the superconducting heat capacity and a reduced normalized jump in the specific heat at $T_c$. A two-band model is proposed to explain these properties and previously reported anomalous properties of superconducting ternary iron silicides.

• Received 18 October 1982

DOI:https://doi.org/10.1103/PhysRevB.27.2800