Nonmagnetic impurity effects in the decorated shastry-sutherland compound Cd(Cu_1-xZn_x)₂(BO₃)₂ (0 ≤ x ≤ 0.2)

We investigate the nonmagnetic impurity effects on the structural and the magnetic properties of the decorated Shastry-Sutherland compound Cd(Cu_1-xZn_x)₂(BO₃)₂ (0 ≤ x ≤ 0.2) by using X-ray diffraction, magnetic susceptibility, high-field magnetization, and electron spin resonance measurements. With increasing Zn content x, the lattice parameters and the g-factors are systematically reduced without any accompanying structural anomaly. We find that Zn substitution leads to an almost linear decrease in the Néel temperature, as well as in the spin-flop transition and the half-step magnetization field. However, the Curie-Weiss temperature hardly varies with x. Our study suggests that intra-tetramer couplings are not essential in determining the magnetic properties of the Zn-substituted samples, unlike other frustrated quantum magnets. Rather, unfrustrated, inter-tetramer coupling is responsible for the x dependence of the magnetic behaviors.