Mechanism of Ferromagnetic Ordering of Mn Chains in CaMnGe2O6 Clinopyroxene

Abstract

The electronic and magnetic properties of clinopyroxene CaMnGe2O6 were studied using density function calculations within the GGA + U approximation. It is shown that anomalous ferromagnetic ordering of neighboring chains is due to a “common-enemy” mechanism. Two antiferromagnetic exchange couplings between nearest neighbors within the Mn-Mn chain and interchain coupling via two GeO4 tetrahedra suppress antiferromagnetic exchange via single GeO4 tetrahedron and stabilize ferromagnetic ordering of Mn chains. © 2019, Pleiades Publishing, Inc.