Cooperative ordering of gapped and gapless spin networks in Cu2Fe2Ge4O13

Phys Rev Lett. 2004 Aug 13;93(7):077202. doi: 10.1103/PhysRevLett.93.077202. Epub 2004 Aug 9.

Abstract

The unusual magnetic properties of a novel low-dimensional quantum ferrimagnet Cu2Fe2Ge4O13 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.