Possible charge-density wave transition in ${\text{PrPt}}_2{\text{Si}}_2$

The physical properties of the ternary intermetallic compound ${\text{PrPt}}_2{\text{Si}}_2$ have been investigated by specific-heat and electrical-resistivity measurements under pressure up to 2.85 GPa. Two phase transitions at $T_0=88\text{K}$ and $T_x=54\text{K}$ are inferred from anomalies in the electrical resistivity. Only the transition at $T_0$ is visible in the specific-heat data. A strong thermal hysteresis suggests a first-order character of both transitions. The resistivity anomaly at $T_0$ has the resemblance to a charge-density wave transition. Furthermore, low-temperature powder x-ray diffraction data do not show any signature of a structural phase transition. The nonmagnetic character of both transitions is confirmed by the absence of a signature in magnetic susceptibility and a magnetic field independent transition temperature. Application of pressure suppresses $T_0\left(p\right)$ but has a very weak effect on $T_x\left(p\right)$.

Figure 1

(Color online) Specific-heat data, $C\left(T\right)$, of ${\text{PrPt}}_2{\text{Si}}_2$ taken on cooling and heating cycles, respectively. The upper inset shows $C\left(T\right)$ between 35 and 70 K. The position of the $T_x$ anomaly observed in the electrical resistivity is indicated by an arrow. The lower inset displays an expanded view of the region near $T_0$.

Figure 2

(Color online) Temperature dependence of electrical resistivity, $\rho \left(T\right)$, of ${\text{PrPt}}_2{\text{Si}}_2$. The upper inset shows the magnetoresistance $\Delta \rho /{\rho }_0$ up to 10 T. The lower inset presents the anomalies in the resistivity in detail. The arrows denote the phase transitions at $T_0$ and $T_x$.

Figure 3

(Color online) $\rho \left(T\right)$ of ${\text{PrPt}}_2{\text{Si}}_2$ at different applied pressures measured on cooling (closed symbols) and on heating cycles (open symbols), respectively. The arrows indicate the direction of temperature change. Inset: $d\rho \left(T\right)/dT$ at $p=0$ and 2.85 GPa. The arrows in the inset mark the transitions at $T_0$ and $T_x$. At 2.85 GPa $T_0$ and $T_x$ cannot be defined unambiguously anymore.

Figure 4

(Color online) $T\text{−}p$ phase diagram of ${\text{PrPt}}_2{\text{Si}}_2$: the transition temperatures $T_0\left(p\right)$ and $T_x\left(p\right)$ determined from the resistivity data on heating are presented. The lines are guide to the eyes.