Spin-Peierls Transition in Ce Compounds

Abstract

A possible spin-Peierls (dimerization) transition in Ce Compounds is investigated theoretically, in connection with the novel phase transition recently reported to occur in CeRu 2 Al 10 . It is pointed out that one-dimensional zigzag chains are profiled by connecting nearest-neighbor (n.-n.) Ce ions in this compound. If only the RKKY interactions between n.-n. Ce 3+ ions are considered in the mean-field approximation, a spin-Peierls transition occurs at T =27 K for the zero-temperature gap parameter Δ 0 =90 K, regardless of the magnetic anisotropy. The characteristics of CeRu 2 Al 10 can be accounted for semiquantitatively, including the finite value of susceptibility for T →0 K due to a Van-Vleck contribution of the excited states of the crystalline electric field at ≈10 2 K above the ground-state doublet.