Possible room-temperature ferromagnetism in SnO2 nanocrystalline powders with nonmagnetic K doping

Sn1 − xKxO2 nanocrystalline powders were synthesized by the sol–gel method. The room-temperature ferromagnetism was observed in K-doped samples, and the saturation magnetization increases with the K concentration. It indicates the ferromagnetism induced by holes injecting is possible. First-principles calculations were employed to analyze the effect of defects on the structural and magnetic properties. Taking into account the structural and valence state characterization, the inhomogeneous distribution of dopants and the holes compensation effect of K and H interstitials in crystal were thought to play important roles in reducing the magnetic moments in samples.

► K-doped SnO2 nanocrystalline powders were synthesized by sol–gel method.
► Prepared powders are single phase with rutile structure.
► Room-temperature ferromagnetism was observed.
► The distribution of dopants and the hole-compensation effect of interstitial atoms were thought to reduce magnetic moments.