Interface mixing and its impact on exchange coupling in exchange biased systems

Abstract

Exchange bias and interlayer exchange coupling are interface driven phenomena. Since an ideal interface is very challenging to achieve, a clear understanding of the chemical and magnetic natures of interfaces is pivotal to identify their influence on the magnetism. We have chosen NiFe/CoO(t )/Co trilayers as a model system, and identified non-stoichiometric Ni-ferrite and Co-ferrite at the surface and interface, respectively. These ferrites, being ferrimagnets typically, should influence the exchange coupling. However, in our trilayers the interface ferrites were found not to be ferro- or ferri-magnetic; thus having no observable influence on the exchange coupling. Our analysis also revealed that (i) interlayer exchange coupling was present between NiFe and Co even though the interlayer thickness was significantly larger than expected for this phenomenon to happen, and (ii) the majority of the CoO layer (except some portion near the interface) did not contribute to the observed exchange bias. We also identified that the interlayer exchange coupling and the exchange bias properties were not interdependent.

Surface engineering with Ar+/O2+ ion beam bombardment: Tuning the electronic and magnetic behavior of Ni80Fe20/La0.7Sr0.3MnO3/SrTiO3(001) junctions

“…13. The Ar-bombarded (herein referred to as Ar-LSMO) and the O 2+ /Ar + bombarded (herein referred to as O 2 -Ar-LSMO) LSMO layer were obtained by treatment with argon (Ar) or a mixture of oxygen (O 2 ) and Ar gases (O 2 /Ar ∼35%) from an End-Hall ion source (V EH = 70 V, 500 mA) 21,22 for 20 min each in order to etch away (etching rate ∼0.3 nm/min) the outermost atomic layers of the LSMO surface.…”

Обменные взаимодействия в гетероструктурах NiFe/Ta/IrMn в условиях дефицита Ta

“…Наличие у этих металлов f -оболочек, обладающих высоким значением орбитального момента, позволяет усиливать обмен между слоями магниторезистивных элементов за счет увеличенной энергии спин-орбитального взаимодействия. Мы полагаем, что увеличение поля смещения в структурах с немагнитной прослойкой Ta связано с РККИ компонентой обмена смещения, доказательства существования которой рассматривались в работах [36,37].…”

Interface Modeling Leading to Giant Exchange Bias from the CoO/CoFe2O4 Quantum Dot Heterostructure

“…However, it has been known that atomic intermixing at the interface or the sharpness of the interface plays an important role in the exchange coupling , between AFM/FM heterostructures. Dimitriadis et al have shown theoretically the atomic scale roughness at the interface that leads to the reduction of uncompensated spins resulting in suppression of H E .…”