Antiferromagnetic long-range order in Cu_{1-x}Zn_xGeO_3 with extremely low Zn concentration

TL;DR

This study investigates the emergence of antiferromagnetic long-range order in Cu_{1-x}Zn_xGeO_3 at extremely low Zn concentrations, revealing order persists without a critical concentration and identifying the Neel temperature.

Contribution

It provides the first detailed measurements of antiferromagnetic order in Cu_{1-x}Zn_xGeO_3 at very low Zn doping levels, showing order occurs without a critical concentration.

Findings

Antiferromagnetic order exists down to x=1.12×10^{-3}.

No critical concentration for antiferromagnetic order was found.

Neel temperature as low as 0.0285 K observed.

Abstract

We have measured the magnetic susceptibilities of single crystals of Cu_{1-x}Zn_xGeO_3 with extremely low Zn concentration (x) lower than x=5x10^{-3} at very low temperatures to investigate the spin-Peierls and antiferromagnetic transitions. The results show that the undoped CuGeO_3 has no antiferromagnetic phase down to 12 mK and there exists an antiferromagnetic long-range order with the easy axis along the $c$ axis for x down to 1.12(2)x10^{-3}. The minimum observed Neel temperature was 0.0285 K for x=1.12(2)x10^{-3} sample. From the concentration dependence of the Neel temperature it is concluded that there is no critical concentration for the occurrence of the antiferromagnetic long-range order.