New magnetic regime in hematite hollow spheres

Abstract A new magnetic regime is presented in hematite hollow spheres. The numerous dangling bonds, formed in the H⁺ etching process during fabrication, endow the surfaces of the primary particles with paramagnetic and ferrimagnetic attributes. The freezing and coupling of these surface states have profound effect on the magnetic performance of the host hematite spheres – including enhanced ferromagnetism, a peculiar variation of thermal remanent magnetization, and an exchange bias training effect, which may find their potential applications in spintronic fields. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)