Antiferromagnetic ground state and heavy-fermion behavior in Ce2Pt2Pb

Specific heat, magnetization, and electrical resistivity have been studied on single crystalline samples of ${\mathrm{Ce}}_{2}{\mathrm{Pt}}_{2}\mathrm{Pb}$. These results clearly indicate that ${\mathrm{Ce}}_{2}{\mathrm{Pt}}_{2}\mathrm{Pb}$ undergoes an antiferromagnetic transition at approximately 3.4 K under a zero magnetic field. The magnetic field induces another ordered phase when the field is applied along the $\ensuremath{\langle}100\ensuremath{\rangle}$ or $\ensuremath{\langle}110\ensuremath{\rangle}$ directions of the crystallography, whereas we have not found another ordered phase along the $\ensuremath{\langle}001\ensuremath{\rangle}$ direction of the field. The specific heat and the magnetization along three directions of the field reveal an easy-plane type magnetic anisotropy even in the antiferromagnetic phase. The magnetic structures of the ordered phases are discussed from the standpoint of macroscopic measurement, which results in a helical magnetic structure as a reasonable scenario. A large Sommerfeld coefficient of the specific heat and squared-temperature dependence of the electrical resistivity strongly suggest construction of the heavy-fermion state in ${\mathrm{Ce}}_{2}{\mathrm{Pt}}_{2}\mathrm{Pb}$, while the influence of the frustration is hardly found.