Evidence for a metamagnetic transition in the heavy fermion system CeTiGe

Systems located close to a quantum critical point are of high interest, because low lying quantum fluctuations (QF’s) can lead to new physical phenomena. The compound CeTiGe crystallizes in the CeFeSi structure type, which presents some (2D) character enhancing QF’s. Our first detailed investigations of C_p(T), Chi(T), and rho(T) at low temperatures for CeTiGe indicate that it is a new paramagnetic heavy fermion system with an enhanced Sommerfeld - coefficient gamma₀ ≈ 0.3 J/(K²mol). Further analyses using the Coqblin-Schrieffer (CS) model showed that the whole J = 5/2 multiplet is involved in the formation of the ground state. The CS - model predicts a broad s-shaped magnetization at high fields and to study this we extended our investigation to measurements under high magnetic field. Here we present the results of magnetization measurements M vs. B in fields up to 14 T performed in a commercial Physical Property Measurement System (PPMS®) and additional data obtained in pulsed high fields up to 60 T performed at the Dresden high magnetic field laboratory (HLD). Instead of the expected behavior these measurements revealed a steplike metamagnetic transition (MMT) at a critical field of μ₀H_c ≈ 12.5 T of the size ΔM ~ 0.74 μ_B/Ce for T = 1.4 K. Thus CeTiGe is the second paramagnetic Ce - based Kondo lattice besides CeRu₂Si₂ showing a clear MMT below 20 T. In contrast to CeRu₂Si₂, CeTiGe shows a hysteresis at the MMT. We shall further present the effect of substitution La for Ce on this metamagnetic transition.