Tuning the magnetic anisotropy in CeRhIn5 via Gd substitution.

In strongly correlated materials, the presence of defects may fundamentally affect both macroscopic and microscopic properties of the system. Here we investigate the effect of Gd substitution in the Kondo antiferromagnet CeRhIn5. At a concentration of only 11% Gd, the magnetic anisotropy of CeRhIn5 is drastically reduced at high temperatures, whereas its antiferromagnetic transition, TNCe=3.8 K, is linearly suppressed with Gd at low temperatures. The extrapolation of TNCe to zero temperature occurs at a critical concentration of xc~0.63, which is above the two-dimensional percolation limit found in Ce1-xLaxRhIn5 (xc~0.4), but very close to the three-dimensional percolation limit found in Gd1-xLaxRhIn5 and Ce1-xLaxIn3 (xc~0.65), in agreement with the more isotropic magnetic response. [ABSTRACT FROM AUTHOR]