We have investigated the anomalous ordered phase of CeTe under high pressure, which has been suggested to be an antiferroquadrupole ordered phase. An anisotropic magnetic phase diagram has been obtained from magnetization and specific heat measurements for the three main field directions along [100], [110], and [111]. We discuss the magnetic phase diagram using a two-sublattice mean-field calculation including antiferromagnetic and antiferroquadrupolar interactions. The anomalous ordered phase can be interpreted as an antiferromagnetic ordered phase, which is strongly affected by the antiferroquadrupolar interaction through the off-diagonal matrix element between the Γ7 crystal-field ground state and the Γ8 excited state.

This work was supported by Grants-in-Aid for Scientific Research (Nos. 21204456, 21102515, and 2430087) from JSPS and MEXT.