부산대학교 도서관

The magnetic ordering patterns of Rb11 Mn8O16 and Cs3 Mn2O4 were determined by neutron powder diffraction with and without applied magnetic fields. The crystal structures of these compounds exhibit infinite chains of edge-sharing MnO4 tetrahedra with periodically alternating Mn2+ and Mn3+ valence. Both Rb11 Mn8O16 and Cs3Mn2O4 show collinear magnetic order with antiferromagnetic alignment of Mn moments along the chains below the Néel temperatures TN = 38(1) and 13.5(5) K, respectively. In Cs3Mn2O4 the Mn2+ and Mn3+ moments could be separately refined. The full magnetic structure in a zero magnetic field can be viewed as a set of ferrimagnetic chains whose net moments are coupled antiferromagnetically perpendicular to the chain direction. For this compound, we further observe a magnetic field induced transition into a high-field phase with uniformly aligned ferrimagnetic moments. [ABSTRACT FROM AUTHOR]