Fingerprinting the magnetic behavior of antiferromagnetic nanostructures using remanent magnetization curves

TL;DR

This paper uses remanent magnetization curves to identify and analyze the magnetic behavior of antiferromagnetic nanostructures, revealing core-shell structures and distinguishing their magnetic contributions.

Contribution

It introduces a general method using TRM/IRM fingerprints to identify irreversible magnetization in various antiferromagnetic nanostructures, expanding previous specific findings.

Findings

TRM/IRM curves reveal core-shell magnetic structures

Fingerprints distinguish between different magnetic states

Method applicable to multiple AF nanomaterials

Abstract

Antiferromagnetic (AF) nanostructures from Co3O4, CoO and Cr2O3 were prepared by the nanocasting method and were characterized magnetometrically. The field and temperature dependent magnetization data suggests that the nanostructures consist of a core-shell structure. The core behaves as a regular antiferromagnet and the shell as a two-dimensional diluted antiferromagnet in a field (2d DAFF) as previously shown on Co3O4 nanowires [Benitez et al., Phys. Rev. Lett. 101, 097206 (2008)]. Here we present a more general picture on three different material systems, i.e. Co3O4, CoO and Cr2O3. In particular we consider the thermoremanent (TRM) and the isothermoremanent (IRM) magnetization curves as "fingerprints" in order to identify the irreversible magnetization contribution originating from the shells. The TRM/IRM fingerprints are compared to those of superparamagnetic systems, superspin glasses and 3d DAFFs. We demonstrate that TRM/IRM vs. H plots are generally useful fingerprints to identify irreversible magnetization contributions encountered in particular in nanomagnets.