An unusual interplay among disorder, Kondo-effect and spin-glass behavior in the Kondo lattices, Ce$_2$Au$_{1-x}$Co$_x$Si$_3$

TL;DR

This study investigates the complex magnetic behavior in Ce$_2$Au$_{1-x}$Co$_x$Si$_3$ Kondo lattices, revealing an unusual suppression of spin-glass freezing near the quantum critical point, contrasting typical expectations.

Contribution

It uncovers a novel magnetic phase diagram in Ce$_2$Au$_{1-x}$Co$_x$Si$_3$, showing suppression of disorder-induced spin-glass behavior near the quantum critical point.

Findings

Spin-glass freezing occurs only at weak coupling compositions.

Disorder effects are suppressed near the quantum critical point.

Long-range antiferromagnetic order emerges as Au is replaced by Co.

Abstract

We report the results of magnetic measurements for the solid solution Ce$_2$Au$_{1-x}$Co$_x$Si$_3$. The results reveal that this solid solution is characterized by a magnetic phase diagram (plot of magnetic transition temperature versus $x$) unusual for Kondo lattices. In particular, the spin-glass freezing induced by disorder is observed only for the compositions at the weak coupling limit; as one approaches the quantum critical point by a gradual replacement of Au by Co, this disorder effect is surprisingly suppressed in favor of long range antiferro-magnetic ordering in contrast to expectations. This unusual interplay between disorder, spin-glass freezing and the Kondo-effect calls for further refinement of theories on competition between magnetism and the Kondo effect.