Abstract
Horizontally shifted and asymmetric hysteresis loops are often associated with exchange-biased samples, consisting of a ferromagnet exchange coupled with an antiferromagnet. In purely ferromagnetic samples, such effects can occur due to undetected minor loops or thermal effects. Simulations of ferromagnetic nanostructures at zero temperature with sufficiently large saturation fields should not lead to such asymmetries. Here we report on micromagnetic simulations at zero temperature, performed on sputtered nanoparticles with different structures. The small deviations of the systems due to random anisotropy orientations in the different grains can not only result in strong deviations of magnetization reversal processes and hysteresis loops, but also lead to distinctly asymmetric, horizontally shifted hysteresis loops in purely ferromagnetic nanoparticles.
Highlights
Nanomaterials 2021, 11, 800. https://The exchange bias (EB) effect describes a phenomenon that occurs in ferromagnet/antiferromagnet systems due to an exchange coupling at the interface and leads to a shift of the hysteresis loop, often in combination with an asymmetry of the loop [1].After firstly being found in Co/CoO core/shell nanoparticles [2], the exchange bias is mostly investigated in thin-film systems [3,4,5,6]
For the repeated simulations we always found vertical shifts of the transverse magnetization to negative values, while the shape of the longitudinal hysteresis varied slightly due to the arbitrary orientation of the magneto-crystalline anisotropy axes in the single grains. This means that for a potential application, the transverse magnetization component—or the magnetization in another direction—may be more suitable than the longitudinal one. Comparing these structures with the first set M1–M4, it must be mentioned that the reliability of magnetization reversal in terms of coercive fields and the shape of the longitudinal hysteresis loop is given in the tessellation structures, if the samples are examined from a macroscopic point of view, i.e., according to their overall magnetization
ML and MT, fordepicted different here tessellations it must be emphasized thatsimulated the effect for some is after setting a large magneticnot field anofequivalent to an exchange bias system, which usually consists of a ferromagnet exchange-coupled to an antiferromagnet, but to a combination of a harder and a softer
Summary
Nanomaterials 2021, 11, 800. https://The exchange bias (EB) effect describes a phenomenon that occurs in ferromagnet/antiferromagnet systems due to an exchange coupling at the interface and leads to a shift of the hysteresis loop, often in combination with an asymmetry of the loop [1].After firstly being found in Co/CoO core/shell nanoparticles [2], the exchange bias is mostly investigated in thin-film systems [3,4,5,6]. Very similar results were found in the sample M3 at an angle of 0◦ (not shown here), where three different magnetization reversal processes were observed in subsequent simulations.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
