Asymmetric Magnetization Reversal in Exchange-Biased Hysteresis Loops

Abstract

Polarized neutron reflectometry is used to probe the in-plane projection of the net-magnetization vector M of polycrystalline Fe films exchange coupled to twinned (110) MnF 2 or FeF 2 antiferromagnetic (AF) layers. The magnetization reversal mechanism depends upon the orientation of the cooling field with respect to the twinned microstructure of the AF, and whether the applied field is increased to (or decreased from) a positive saturating field; i.e., the magnetization reversal is asymmetric. The reversal of the sample magnetization from one saturated state to the other occurs via either domain wall motion or magnetization rotation on opposite sides of the same hysteresis loop.

Emergence of noncollinear anisotropies from interfacial magnetic frustration in exchange-bias systems

“…In general, rotation processes are more relevant in one branch of the hysteresis loop, in which a larger density of domains during irreversible domain nucleation processes is also observed. 25,28,29,35,36 For some systems, rounded transitions in M ʈ and larger M Ќ values are found in the descending branch, 20,21,[25][26][27][28][34][35][36] where the field is applied parallel to the exchange-bias direction, while other systems display the opposite behavior. [21][22][23][24][25][29][30][31][32][33] Our results indicate that this discrepancy is related to the difference between a collinear and a noncollinear anisotropy case.…”

“…Asymmetries in the magnetization reversal have been observed for many FM/AFM systems with both in-plane [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34] and perpendicular 35,36 anisotropy for the FM layer. In general, rotation processes are more relevant in one branch of the hysteresis loop, in which a larger density of domains during irreversible domain nucleation processes is also observed.…”

Giant vertical magnetization shift induced by spin canting in a Co/Ca2Ru0.98Fe0.02Yuan1, Li2, Qi3 et al. 2013Phys. Rev. B281110View full textAdd to dashboardCite

“…Indeed, an asymmetry between the two branches of the hysteresis loop for descending and ascending magnetic fields is generally characteristic of EB systems 3,[24][25][26] . However, the asymmetry displayed in Fig.…”

Perpendicular exchange bias in ferrimagnetic spin valves

“…Yet, these two magnetic components are difficult to access experimentally with laboratory tools because of a virtually vanishing magnetization of AF layers and a small volume of the magnetic interface. Important progress has been made by involving neutron and Xray techniques to study the bulk part of the pinning layer and the interfacial magnetism [6][7][8][9][10][11][12][13] . For instance, in an archetypal CoO/FM bilayer, neutron scattering has revealed the origin of reduced EB.…”