Antiferromagnet to ferromagnet crossover driven by nonmagnetic Co doping in heavy-fermion YbRh3⁢Si7

Abstract

YbRh3⁢Si7 is a heavy fermion compound that stands out among Yb-based heavy fermions, with its relatively high magnetic ordering temperature and large Yb-Yb distance. To investigate the origin of the magnetic properties in this compound, we synthesized Co doped YbRh3⁢Si7, achieving a record-high ferromagnetic ordering temperature 𝑇C=15.6K, only limited by the Co solubility of 20%. Furthermore, we find a crossover from antiferromagnetic to ferromagnetic order with Co doping. The specific heat and magnetotransport measurements show heavy fermion behavior and the persistence of Kondo latticelike behavior in the Yb⁢(Rh1−𝑥⁢Co𝑥)3⁢Si7 series.