The intermetallic compounds ${\mathrm{LaRu}}_2$ and ${\mathrm{CeRu}}_2,$ as well as several quasibinary systems ${\mathrm{Ce}}_{1-x}{\mathrm{La}}_x{\mathrm{Ru}}_2,$ were synthesized at a pressure of 8 GPa. The x-ray diffraction data showed the pure cubic $C15\mathrm{}$ structure for all samples. The x-ray absorption measurements gave the value 3.23 for the Ce valence. Time-differential perturbed angular correlation measurements with the ${}^{111}\mathrm{In}$-doped samples have shown (i) ${}^{111}\mathrm{In}$ substituted for Ru; (ii) in ${\mathrm{LaRu}}_2$ a single value of the quadrupole frequency ${\nu }_Q=234\mathrm{}$ MHz for the daughter ${}^{111}\mathrm{Cd}$ nuclei was observed; (iii) in ${\mathrm{CeRu}}_2$ two distinct equally populated sites for ${}^{111}\mathrm{Cd}$ were revealed with ${\nu }_Q=218\mathrm{}$ and ${\nu }_Q=153\mathrm{}\hspace{0.5em}\mathrm{MHz}.$ The low-temperature magnetic measurements showed that magnetic moments about $0.3{\mu }_B$ per formula unit are inherent in all samples and indicated at a coexistence of superconductivity and magnetic ordering. In particular, the magnetic and superconducting correlations are developing, most probably, in the same system of ruthenium $4d$ electrons.

• Received 15 August 2001

DOI:https://doi.org/10.1103/PhysRevB.65.174513