Unexpected magnetism in nanomaterials

Conventional magnetic order in a material requires the partially filled d or f bands. The exchange interactions between the electrons in these partially filled bands give rise to a magnetic order. However, the discovery of unexpected magnetism observed in some nanomaterials, which have the d and f shells either completely empty or full, has challenged our understanding of magnetism in conventional materials. The magnetism in nanomaterials shows the effects of reduced dimensions, reduced coordination of atoms at the surface and some quantum effects which dominate at low dimensions. In this review paper we give a brief review and discuss the unexpected magnetism experimentally observed and/or theoretically predicted in nanomaterials of conventional magnetic and nonmagnetic bulk materials.