Pressure-induced magnetic instability inCe2Rh3Ge5

Abstract

A pressure-induced magnetic-nonmagnetic transition in an antiferromagnet Ce 2 Rh 3 Ge 5 has been investigated by the measurements of the resistivity , magnetic susceptibility , and specific heat on a single crystal down to 0.3 K. With increasing pressure, the Néel temperature T N is suppressed and disappears at P c ϭ0.45 GPa. For PϾ P c , the deviation from the Fermi-liquid behavior is observed in both (T) and (T): (T)ϭ 0 ϩAT n (nХ1.45) and (T)ϭ 0 ϪDT m (mХ0.27). Even for PϾ3 P c both n and m hardly change, i.e., no recovery of the Fermi-liquid state. This fact is in contrast with the recovery in many of Ce-based antiferromagnets at PϾ2 P c . The magnetization hardly decreases with pressure up to 1.2 GPa, suggesting that the cerium local moments still remain even far from the quantum critical point. Moreover, the Kondo temperature T K increases weakly from 10 K at Pϭ0 to 13 K at Pϭ0.57 GPa. These findings indicate the important role of short-range magnetic correlations in the revised Doniach phase diagram.

Theory of the Kondo lattice: competition between Kondo effect and magnetic order

“…It is rather difficult to deduce experimentally the Kondo temperature especially in Kondo systems that are close to be magnetic and, therefore, to compare the preceding theoretical results with the experimental data. However, we can deduce from experimental results in CeRh 2 Si 2 [13], CeRu 2 Ge 2 [23,24] or Ce 2 Rh 3 Ge 5 [25] that the pressure dependence of T K observed in these systems is different from the single-impurity case, in good agreement with our model. But, on the other hand, the lattice Kondo temperature is closely following the single-impurity one in the other cerium and all ytterbium compounds.…”

Band-filling effects on Kondo-lattice properties

“…This result can account for the pressure dependence of T K observed in CeRh 2 Si 2 , 3 CeRu 2 Ge 2 , 5,6 or more recently Ce 2 Rh 3 Ge 5 . 8 On the other hand, depend-ing on the relative values of J H and J K , as well as on the band-filling, the lattice Kondo temperature can closely follow the single-impurity one, as observed in many cerium and all ytterbium compounds. Further experiments are needed to better understand the conditions yielding a Kondo temperature for the lattice much different than the single-impurity one.…”

Anisotropic magnetic properties of

“…The splitting energies between the ground state and the first (second) doublets are D 1 ¼ 87 K (and D 2 ¼ 504 K), respectively, which are the same values estimated from the Schottky anomaly. Ce 2 Ni 3 Ge 5 and Ce 2 Rh 3 Ge 5 also exhibit the similar large splitting energies [4,8].…”