Antiferromagnetic behavior in CeCo${}_9$Ge${}_4$

Abstract

We investigate the novel intermetallic ternary compounds \emph{R}Co${}_9$Ge${}_4$ with \emph{R} = La and Ce by means of $X$-ray diffraction, susceptibility and specific heat measurements. CeCo${}_9$Ge${}_4$ crystallizes in the space group $I$ 4/ $mcm$ and is characterized by the coexistence of two different magnetic sublattices. The Ce-based sublattice, with an effective moment close to the expected value for a Ce${}^{3+}$-ion, exhibits a magnetically ordered ground state with $T_{\mathrm{N}}=12.5$ K. The Co-based sublattice, however, exhibits magnetic moments due to itinerant 3$d$ electrons. The magnetic specific heat contribution of the Ce-sublattice is discussed in terms of a resonance-level model implying the interplay between an antiferromagnetic phase transition and the Kondo-effect and an underlying Schottky-anomaly indicating a crystal field level scheme splitting into three twofold degenerated micro states ($\hat{I}{”}_1=69$ K, $\hat{I}{”}_2=133$ K).

4 pages, 3 figures, conference SCES09