ESR of coupled spin-1/2 chains: unveiling zig-zag-type interchain correlations

TL;DR

This study uses electron spin resonance to uncover the zig-zag interchain coupling in a spin-1/2 Heisenberg antiferromagnetic chain, revealing its impact on magnetic ordering and frustration effects.

Contribution

It identifies the zig-zag interchain interaction as dominant in Cu(C$_4$H$_4$N$_2$)(NO$_3$)$_2$, linking experimental ESR data with theoretical modeling to explain low-temperature magnetic order.

Findings

Zig-zag interchain coupling is crucial in the material.

Interchain interaction causes geometrical frustration.

Low-temperature order is an incommensurate spiral state.

Abstract

By means of electron spin resonance investigations we revealed the crucial role of the interchain coupling in the spin dynamics of the spin-1/2 Heisenberg antiferromagnetic (AF) chain material copper-pyrazine-dinitrate, Cu(C$_4$H$_4$N$_2$)(NO$_3$)$_2$. We found that the dominating interchain interaction is of a zig-zag type. This interaction gives rise to geometrical frustration effects and strongly influences the character of AF ordering. Combining our experimental findings with the results of a quasiclassical approach we argue that at low temperatures the system orders in an incommensurate spiral state.