Magnetism in frustrated Kondo and non-Kondo intermetallics: CeInCu2 versus NdInCu2

Single crystalline intermetallics CeInCu2 and NdInCu2, where the rare earth ions occupy geometrically frustrated fcc lattice of Heusler-type structure, have been studied comparatively to shed light on the ground-state magnetism derived from Kondo physics and/or spin frustration competing with the Ruderman-Kittel-Kasuya-Yosida interaction. CeInCu2 is distinct from NdInCu2 due to the significant Kondo effect that is absent in the latter. They order antiferromagnetically at TN approximate to 1.4 and 2.0 K with large paramagnetic Curie-Weiss temper-ature of -35.4 K and -41.1 K, respectively. The electronic specific-heat coefficient gamma = C/T (T -> 0) = 870 mJ mol-1 K-2 in CeInCu2 is significantly enhanced, much larger than 180 mJ mol-1 K-2 of the latter that is also enhanced albeit its non-Kondo nature. For both compounds, the Kadowaki-Woods ratio deviates greatly from the standard value expected from a Kramers doublet ground state, which, however, can be restored if one considers a smaller but still sizable gamma estimated from the paramagnetic state. Likewise, the Kondo temperature of CeInCu2 is revised to be TK approximate to 13 K that is double the literature values, manifesting a major effect of spin frustration to low-temperature thermodynamics beyond the Kondo physics. Similarities between the two compounds is also noticed in their temperature-field phase diagrams in spite of their thermodynamic distinctions in the thermal expansion and the Gruneisen ratio, which are much more sensitive to Kondo hybridization than to geometrical frustration.

Automated summary

Comparative study on single crystalline intermetallics CeInCu2 and NdInCu2 reveals similarities in their temperature-field phase diagrams, despite differences in thermal expansion and Gruneisen ratio that are more sensitive to Kondo hybridization. Both compounds exhibit ground-state magnetism derived from spin frustration and/or Kondo physics.