Behavior of magnetic ordering and the Kondo effect in the alloys Ce2Rh1-xCoxSi3

The results of magnetic susceptibility, electrical resistivity (rho), and heat-capacity measurements as a function of temperature are reported for the alloys, Ce2Rh1-xCoxSi3, crystallizing in an AlB2-derived hexagonal structure. Ce2RhSi3 exhibits antiferromagnetic ordering at 7 K. The Neel 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 Neel 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.