Synthesis and magnetic properties of the thin film exchange spring system of MnBi/FeCo

Sabet, Sareh; Hildebrandt, Erwin; Alff, Lambert

doi:10.1088/1742-6596/903/1/012032

Cited by 3 publications

(1 citation statement)

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“…For exchange spring heterostructures with MnBi as hard magnetic phase, to our knowledge there have been only a few recent studies investigating the synthesis and magnetic properties of the resulting bilayers [16][17][18][19]. Although theoretical calculations have proven the concept of exchange spring magnets to increase the overall magnetic properties, according to the few available studies the coupling between the MnBi and Fe x Co 1−x layers is incoherent for magnetic layers thicker than ∼ 4 nm [16][17][18][19]. This is also evident from the small shoulder observed around zero field on the hysteresis loops measured in all above mentioned studies where the two layers do not behave as a single magnetic phase.…”

Section: Introductionmentioning

confidence: 99%

Impact of interface structure on magnetic exchange coupling in MnBi/FexCo1−x bilayers

et al. 2018

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In this study we investigate the magnetic exchange coupling behavior in MnBi/FeCo system at the hard/soft interface. Exchange spring MnBi/FexCo1−x (x = 0.65 and 0.35) bilayers with various thicknesses of the soft magnetic layer were deposited onto quartz glass substrates in a DC magnetron sputtering unit from alloy targets. According to magnetic measurements, using a Co-rich layer leads to more coherent exchange coupling with optimum soft layer thickness of about 1 nm. In order to take into account the effect of structural factors at the hard/soft interface which can deteriorate the exchange coupling for thicker soft magnetic layers, we have combined cross-sectional High Resolution Transmission Electron Microscopy (HR-TEM) analysis with DFT calculations and micromagnetic simulations. DFT calculations predict formation of a polycrystalline FeCo layer with coexisting crystalline (110) and disordered (randomly-oriented) phases which is confirmed by HR-TEM images. Moreover, our micromagnetic simulations show how the thickness of the FeCo layer and the interface roughness between the hard and soft magnetic phases both control the effectiveness of exchange coupling in MnBi/FeCo system. Our method can be applied to study other exchange spring systems.

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