Doping Dependence of the Structural and Magnetic Properties of CeCu$_{6-x}$T$_{x}$ (T = Ag, Pd)

CeCu$_{6-x}$Au$_x$ is a well-known heavy fermion system that exhibits an antiferromagnetic quantum critical point(QCP) at x $\sim$ 0.1. The end-member, CeCu$_6$ undergoes a structural transition, which is suppressed as Cu is partially substituted by Au in CeCu$_{6-x}$Au$_x$: the critical concentration being at x$\sim$0.1. This critical point occurs in close proximity to the antiferromagnetic QCP. Here, we study related systems, CeCu$_{6-x}$Ag$_x$ and CeCu$_{6-x}$Pd$_x$, to determine more globally the role of structural degrees of freedom in the observed critical behavior. For magnetically ordered compositions of CeCu$_{6-x}$Ag$_x$ and CeCu$_{6-x}$Pd$_x$, we find a long-range order with the wave-vector similar to that observed in CeCu$_{6-x}$Au$_x$. The structural transition temperature of CeCu$_{6-x}$Ag$_x$ decreases linearly with Ag concentration until the transition is completely suppressed at x$\sim$0.1. In contrast, moderate Pd-doping does not affect the structural transition, which is observed in CeCu$_{6-x}$Pd$_x$ with x $\leq$ 0.4.