Structural and magnetic properties of biphasic La2NiMnO6

Abstract

The manipulation of magnetic/elecric properties by an electric/magnetic field in magnetoelectric multiferroic materials has driven significant research interest, with the aim of realizing their transformative technological potential. One promising candidate of this type is La2NiMnO6 (LNM). There is a long controversy about its crystal structure and oxidation states of Ni and Mn. Some people have reported this material as a mixed phase system viz., Pbnm + R-3c, whereas some researchers have reported it as a single-phase material ordered in P21/n symmetry. In addition to this, there are also reports of Pbnm + P21/n and P21/n + R-3c symmetries present in it. So in order to investigate its existence of single phase and mixed phase, structural and magnetic properties in double perovskites La2NiMnO6 (LNM) were studied using X-ray diffraction (XRD), neutron diffraction and magnetisation measurements. LNM is synthesised by sol-gel auto combustion method using Pechini’s technique, by varying sintering time at 1200°C, i.e. 4 hours (4H), 6 hours (6H), 12 hours (12H) and 24 hours (24H). The Rietveld analysis of XRD data showed the biphasic (monoclinic + orthorhombic) nature of all the samples. The volume fraction of both the phases varies with varying sintering time. This observation is also confirmed by neutron diffraction data. 12H sample shows the highest magnetisation as compared to other samples.