Magnetic order induced by magnetic impurities in the Haldane chain compound SrNi2V2O8

Understanding the topological properties of Haldane spin systems offers promising avenues for exploring exotic quantum phases. We investigate the impact of S = 5/2 Mn2+ impurities on the magnetic properties of SrNi2V2O8, a well-known Haldane spin gapped system. Structural characterizations of SrNi2-xMnxV2O8 (x = 0.05, 0.15, 0.30 and 0.60) through Rietveld analyses of X-ray diffraction data confirm the preservation of the I41cd space group for all studied x , along with a preferential insertion of Mn2+ ions into Ni2+ sites. Magnetic susceptibility and magnetization data unveil a magnetic transition occurring in the temperature range of T = 93-99.3 K for x = 0.05-0.60. Dielectric data evince the absence of coupling between magnetic and ferroelectric phases. Notably, the magnetic ordering temperature varies little over a wide range of Mn concentrations, while notable anomalies are observed at x = 0.15. This peculiar behavior suggests that, across low-to-high concentrations, disorderinduced magnetic moments compete with the formation of spin singlets between the nearest Mn2+ impurities, which cancel out the magnetic moments.