Behavior of magnetic ordering and the Kondo effect in the alloys Ce₂Rh_1−xCoxSi₃

Abstract

The results of magnetic susceptibility, electrical resistivity (ρ), and heat-capacity measurements as a function of temperature are reported for the alloys, Ce₂Rh_1−xCo_xSi₃, crystallizing in an AlB₂-derived hexagonal structure. Ce₂RhSi₃ exhibits antiferromagnetic ordering at 7 K. The Néel temperature decreases gradually with the increase in Co concentration. For x 0.6, no magnetic ordering is observed down to 0.5 K. Interestingly, the x=0.6 alloy exhibits signatures of non-Fermi-liquid behavior, while the Co end member is a Fermi liquid. Thus, a transformation of magnetic-ordering state to nonmagnetism via non-Fermi-liquid state by isoelectronic chemical doping is evident in this solid solution. The heat-capacity data reveal a dominant role of Kondo compensation in the magnetically ordered state. The electrical resistivity data for x=0.2 and 0.3 alloys show an upturn at respective Nèel temperatures, establishing the formation of a magnetism-induced pseudogap for these intermediate compositions alone as though there is a gradual Fermi surface transformation as the quantum critical point is approached.