  We have investigated the magnetic and transport properties of a ternary
intermetallic compound PrRuSi3 using dc magnetization, ac susceptibility,
specific heat, electrical resistivity, neutron diffraction, inelastic neutron
scattering and muSR measurements. The magnetic susceptibility and specific heat
data reveal the signatures of spin-glass behavior in PrRuSi3 with a freezing
temperature of 9.8 K. At low magnetic fields, we observe two sharp anomalies
(at 4.9 and 8.6 K) in magnetic susceptibility data. In contrast, the specific
heat data show only a broad Schottky-type anomaly centered around 10 K.
However, muSR reveals very low frequency coherent oscillations at 1.8 K with an
onset of fast relaxation below 12 K indicating a long range magnetically
ordered ground state with very small moment. On the other hand, no magnetic
Bragg peaks are observed in low temperature neutron diffraction data at 1.8 K.
These two contradictory ground states, spin-glass versus magnetic order, can be
explained if the spin-glass behavior in PrRuSi3 is considered due to the
dynamic fluctuations of the crystal field levels as has been proposed for
spin-glass behavior in PrAu2Si2. Two sharp inelastic excitations near 2.4 meV
and 14.7 meV are observed in the inelastic neutron scattering (INS) spectra
between 4 K and 50 K. Further, exchange coupling J_ex obtained from the
analysis of INS data with CEF model provides evidence for the spontaneously
induced magnetic order with a CEF-split singlet (Gamma_t4) ground state.
However, the exchange coupling seems to be close to the critical value for the
induced moment magnetism, therefore we tend to believe that the dynamic
fluctuations between the ground state singlet and excited doublet CEF levels is
responsible for spin-glass behavior in PrRuSi3.
