Superconductivity of ZrRuSi prepared at high pressure

Hexagonal ZrRuSi with the ${\mathrm{Fe}}_2$P-type structure (h-ZrRuSi) and orthorhombic ZrRuSi with the ${\mathrm{Co}}_2$P-type form (o-ZrRuSi) were prepared at high temperatures and high pressures. These metal silicides are interesting layer compounds. A resistivity of ZrRuSi was measured at low temperatures. The superconductivity was observed between 7–12 K for h-ZrRuSi and between 3–5 K for o-ZrRuSi. These silicides are superconductors. The resistivity of h-ZrRuSi and h-ZrRuP was measured at various constant temperatures as a function of applied magnetic field. The upper critical field (${\mathit{H}}_{\mathit{c}2}$) obtained from resistance vs magnetic field curves was 1 tesla at 0 K for h-ZrRuSi. This is a surprisingly small value. On the contrary, h-ZrRuP has large ${\mathit{H}}_{\mathit{c}2}$ of 17.5 tesla at 0 K. The physical properties of these superonductors are discussed.