Water-induced and co-filling control induced ferromagnetism in Rb2Ni3S4

The influence of water-immersing on the magnetic behavior ofRb(2)Ni(3)S(4) single crystals grown by the flux method was studied, where the intrinsic substance is non-magnetic because of the low spin state of Ni2+ in a Kagome lattice. The influence of Co-doping to Rb2Ni3S4 was also studied in terms of the local spin density approximation (LSDA) band structure calculation. Residual ferromagnetic moments appeared in specimens immersed into water, as their magnitudes increase depending on the immersion time. The LSDA band structure calculation suggested that Co substitution for Ni allows deriving a novel ferromagnetic behavior