  High value of magnetic moment 0.08 emu/g at room temperature for SnO_2
nanoparticles (NPs) was observed. Surface functionalization with
octadecyltrichlorosilane (OTS) enhanced the saturation magnetic moment of NPs
to an anomalously high value of 0.187 emu/g by altering the electronic
configuration on NPs surface. Surface functionalization also suppressed
photoluminescence (PL) peaks arising from oxygen defects around 2 eV and caused
an increase in the intensities of two peaks near violet region (2.6 - 3 eV). PL
studies under uniform external magnetic field enriched understanding of the
role of OTS. Both OTS and external magnetic field significantly modulated the
luminescence spectra, by altering the surface electronic structure of NPs.
Extra spins on the surface of SnO2 NPs created by the surface functionalization
process and their influence on resultant magnetic moment and luminescence
properties are discussed in details.
