Electrical resistivity of the heavy-fermion system CePtSi under pressure

The electrical resistivity of the heavy-fermion system CePtSi has been measured under pressures up to 15 kbar and at temperatures from 1.2 to 300 K. With increasing pressure P, the room-temperature magnetic resistivity ${\mathrm{\ensuremath{\rho}}}_{\mathit{m}}$ for CePtSi, ${\mathrm{\ensuremath{\rho}}}_{\mathit{m}}$(CePtSi)=\ensuremath{\rho}(CePtSi)-\ensuremath{\rho}(LaPtSi) and the temperature ${\mathit{T}}_{\mathit{m}}$, at which ${\mathrm{\ensuremath{\rho}}}_{\mathit{m}}$ takes a maximum, increase, whereas the ${\mathrm{\ensuremath{\rho}}}_{\mathit{m}}$ at low temperatures (for instance at T=4.2 K) decreases. These results can be understood on the basis of competition between Kondo-lattice behavior and mixed-valence effects scaled by the lattice spacing. The correspondence between the pressure effect in CePTSi and the alloying effect in Ce(${\mathrm{Pt}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Ni}}_{\mathit{x}}$)Si is discussed as a function of unit-cell volume. In addition, a comparison of this compound with other heavy-fermion systems, such as ${\mathrm{CeAl}}_{3}$, ${\mathrm{CeCu}}_{2}$${\mathrm{Si}}_{2}$, and ${\mathrm{CeCu}}_{6}$ is included.