Nature of Magnetic Ordering in Cobalt‐Based Spinels

Abstract

In this chapter, the nature of magnetic ordering in cobalt‐based spinels Co3 O4 , Co2 SnO4 , Co2 TiO4 , and Co2 MnO4 is reviewed, and some new results that have not been reported before are presented. A systematic comparative analysis of various results available in the literature is presented with a focus on how occupation of the different cations on the A‐ and B‐sites and their electronic states affect the magnetic properties. This chapter specifically focuses on the issues related to (i) surface and finite‐size effects in pure Co3 O4 , (ii) magnetic‐compensation effect, (iii) co‐existence of ferrimagnetism and spin‐glass‐like ordering, (iv) giant coercivity (HC ) and exchange bias (HEB ) below the glassy state, and (v) sign‐reversal behavior of HEB across the ferri/ antiferromagnetic Néel temperature (TN ) in Co2 TiO4 and Co2 SnO4 . Finally, some results on the low‐temperature anomalous magnetic behavior of Co2 MnO4 spinels are presented.