Browsing by Author "Zhu, T"

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    90° magnetic coupling in a NiFe/FeMn/biased NiFe multilayer spin valve component investigated by polarized neutron reflectometry
    (American Institute of Physics, 2014-07-17) Callori, SJ; Bertinshaw, J; Cortie, DL; Cai, JW; Le Brun, AP; Zhu, T; Klose, F
    We have observed 90° magnetic coupling in a NiFe/FeMn/biased NiFe multilayer system using polarized neutron reflectometry. Magnetometry results show magnetic switching for both the biased and free NiFe layers, the latter of which reverses at low applied fields. As these measurements are only capable of providing information about the total magnetization within a sample, polarized neutron reflectometry was used to investigate the reversal behavior of the NiFe layers individually. Both the non-spin-flip and spin-flip neutron reflectometry signals were tracked around the free NiFe layer hysteresis loop and were used to detail the evolution of the magnetization during reversal. At low magnetic fields near the free NiFe coercive field, a large spin-flip signal was observed, indicating magnetization aligned perpendicular to both the applied field and pinned layer. © 2020 AIP Publishing LLC.
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    90° magnetic coupling in a NiFe/FeMn/biased NiFe spin valve investigated by polarised neutron reflectometry
    (Australian Institute of Physics, 2014-02-05) Callori, SJ; Zhu, T; Klose, F
    We have used the PLATYPUS reflectometer at ANSTO to perform polarised neutron reflectometry in order to investigate 90° magnetic coupling in a Ni81Fe19/Fe50Mn50/biased Ni81Fe19 spin valve system. Spin valves play an important role in current and developing technological systems, such as spintronics devices or magnetoresistive sensors. For the later usage, perpendicular coupling in a spin valve structure leads to a desired linear, reversible resistance response to an applied magnetic field. The spin valve presented here consists of both free and exchange biased ferromagnetic Ni81Fe19 layers, the later of which is pinned by an antiferromagnetic Ir25Mn75 layer at low applied magnetic fields. The free Ni81Fe19 may be magnetically reversed under low fields, and standard magnetometry measurements on similar systems have suggested perpendicular orientation of the free and biased magnetisations at zero field. Magnetometry measurements, however, are only capable of providing information about the magnetisation within a sample along the direction of the applied field. In contrast, polarised neutron reflectometry (PNR) is capable of resolving the in-plane magnetisation vectors both along and perpendicular to the applied magnetic field as function of layer depth. Here, PNR was used to obtain magnetic vector depth profiles of the spin valve at several applied fields, including low fields near the switching point of the free Ni81Fe19 layer. At these fields a large spin-flip signal was observed in the free layer, indicating magnetisation aligned perpendicular to the external field applied along the pinned layer magnetisation. Both the non-spin flip and spin-flip signals were also tracked around the free layer hysteresis loops and can be used to map the evolution of the free Ni81Fe19 layer during magnetic reversal.