Cooperative ordering of gapped and gapless spin networks in Cu$_2$Fe$_2$Ge$_4$O$_{13}$

TL;DR

This study investigates the magnetic properties of Cu$_2$Fe$_2$Ge$_4$O$_{13}$, revealing it consists of two coupled low-dimensional quantum spin systems, one gapped and one gapless, leading to cooperative magnetic ordering at low temperatures.

Contribution

It demonstrates the coexistence and weak coupling of gapped and gapless spin networks in a single material, providing insight into their cooperative magnetic behavior.

Findings

Identification of two distinct spin subsystems with different energy scales.

Observation of long-range magnetic order due to weak coupling.

Characterization of the material as a low-dimensional quantum ferrimagnet.

Abstract

The unusual magnetic properties of a novel low-dimensional quantum ferrimagnet Cu$_2$Fe$_2$Ge$_4$O$_{13}$ are studied using bulk methods, neutron diffraction and inelastic neutron scattering. It is shown that this material can be described in terms of two low-dimensional quantum spin subsystems, one gapped and the other gapless, characterized by two distinct energy scales. Long-range magnetic ordering observed at low temperatures is a cooperative phenomenon caused by weak coupling of these two spin networks.