Magnetization Study of the Valence Fluctuation Compound Sm₃Te₄ at Very Low Temperatures

The ac susceptibility Χ_ac and the dc magnetization M(H, T) of single crystals of Sm₃Te₄ have been measured at temperatures as low as 70 mK. A cusp is found in Χ_ac at 1.3 K which is slightly lower than the temperature at which a broad peak of the specific heat was previously observed. Distinct irreversibility is observed in M(H, T) below ∼ 1.3 K. The results indicate that the Sm³⁺ moment undergoes a spin glass transition at T_g ∼ 1.3 K. It is likely that the two valence states of Sm²⁺(J = 0) and Sm²⁺(J = 5/2) are randomly frozen at low temperatures in the bcc lattice to effectively form a randomly diluted antiferromagnet.