Competing Magnetic Interactions in the Intermetallic Compound Ho₂Mn₃Si₅

Abstract

The compound Ho2Mn3Si5 exhibits multiple magnetic transitions: (i) an ordering at ~78 K, (ii) a second magnetic transition at ~16 K, and (iii) an anomaly at ~4 K. Its paramagnetic Curie temperature is found to be small but positive. Assuming a free ion effective paramagnetic moment of 10.6µB for Ho3+ ion, the effective paramagnetic moment per Mn in this compound is calculated to be 1.73µB, which indicates the itinerant nature of Mn d electrons. The various transitions in magnetization data are perhaps due to the ordering of rare earth and Mn moments. The magnetization at 2 K in applied fields of up to 7 T has linear field dependence, indicating dominant antiferromagnetic interactions in the system. Neutron diffraction studies point to a complex amplitude modulated incommensurate magnetic structure at 9 K