Low Temperature Magnetic Properties of Ce3Pd20Si6

概要

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Magnetization of a single crystalline Ce3Pd20Si6 was measured at low temperatures down to 90 mK in fields up to 11 T for the three principal directions [100], [110], and [111]. For all directions, two transitions were observed in the temperature variation of the magnetization $M(T)$ at 0.2 T; a broad peak at 0.28 K associated with a phase-III transition, and an upward bending at ${\sim}0.5$ K due to a phase-II ordering from the paramagnetic state (phase-I). The latter critical temperature $T_{\text{I--II}}$ is found to be strongly enhanced in magnetic fields $B$, depending on the field direction, and $T_{\text{I--II}}(B)$ becomes highly anisotropic. These results suggest that phase-II is an antiferroquadrupole state originated from a $\Gamma_{8}$ ground state. By contrast, no appreciable anisotropy is found in the phase-III state. At 90 mK, phase-III collapses by applying a field of ${\sim}0.63$ T for all directions. Above this field, the magnetization curve $M(B)$ becomes strongly anisotropic. The magnetization value per Ce in the phase-I region at 90 mK is apparently smaller than the $\Gamma_{8}$ moment, indicating that either 8c or 4a site has a $\Gamma_{7}$ ground state.
Physical Society of Japanの論文
2010-07-15