Extrinsic negative magnetization and exchange bias: Impact of the SmCrO3 particle size

Abstract

Polycrystalline SmCrO3 with particle sizes between 106 and 527 nm were prepared by controlling the annealing temperature, and the particle size effects on their structural and magnetic properties were systematically investigated. Analysis of magnetic data indicates that the maximum magnetization was enhanced upon increasing the particle size and the negative magnetization observed under nominal zero-field-cooling conditions was caused by a negative trapped field. Interestingly, the exchange bias effect can also be tuned by modulating the particle size. The zero-field-cooling exchange bias field (HEB) and the remnant magnetization shift (MEB) had nonmonotonic relationships with the particle size, whereas the field-cooling HEB and MEB decreased monotonically with increasing particle size. The ratio of Cr3+/Cr6+ and the potential surface spin disorder are discussed based on X-ray photoelectron and Raman spectral results to determine the ferromagnetic/antiferromagnetic contributions, whose interfacial anisotropic energy was considered responsible for the tunable exchange bias. Overall, these results presented herein suggest new ways to optimize the properties of SmCrO3 materials for applications in the magnetic storage.