Abstract
We present a study of the evolution of magnetism from the quantum critical system YbRhSi to the stable trivalent Yb system YbCoSi. Single crystals of Yb(RhCo)Si were grown for and studied by means of magnetic susceptibility, electrical resistivity, and specific heat measurements, as well as photoemission spectroscopy. The results evidence a complex magnetic phase diagram, with a nonmonotonic evolution of and two successive transitions for some compositions resulting in two tricritical points. The strong similarity with the phase diagram of YbRhSi under pressure indicates that Co substitution basically corresponds to the application of positive chemical pressure. Analysis of the data proves a strong reduction of the Kondo temperature with increasing Co content, becoming smaller than for , implying a strong localization of the electrons. Furthermore, low-temperature susceptibility data confirm a competition between ferromagnetic and antiferromagnetic exchange. The series Yb(RhCo)Si provides an excellent experimental opportunity to gain a deeper understanding of the magnetism at the quantum critical point in the vicinity of YbRhSi where the antiferromagnetic phase disappears ().
2 More- Received 23 December 2010
DOI:https://doi.org/10.1103/PhysRevB.83.144405
©2011 American Physical Society