Spin Defects in Spin-Peierls Systems

TL;DR

This paper investigates how introducing non-magnetic zinc impurities into CuGeO3 affects its spin-Peierls state, revealing coexistence with antiferromagnetic order and matching experimental transition temperatures at low doping levels.

Contribution

It demonstrates analytically that spin defects induce coexistence of antiferromagnetic and spin-Peierls states, and calculates doping-dependent transition temperatures and spin gaps.

Findings

Antiferromagnetic order coexists with spin-Peierls state due to spin defects.

Calculated transition temperatures agree with experimental data for low doping.

Doping dependence of spin gap and transition temperature is quantitatively modeled.

Abstract

We examine spin-Peierls systems in the presence of spin defects which are introduced by replacing magnetic ions $Cu^{2+}$ with non-magnetic ones $Zn^{2+}$ in $CuGeO_3$. By using the action for the bosonized Hamiltonian, it is shown directly that the antiferromagnetic state induced by the spin defects coexists with the spin-Peierls states. Further the doping dependences of both transition temperature of spin-Peierls state and the spin gap have been calculated. The transition temperature of the present estimation shows good agreement quantitatively with that observed in $Cu_{1-\de} Zn_\de O_3$ for the region of the doping rate, $\de<0.02$.