The effect of atomic structure on interface spin-polarization of half-metallic spin valves: Co2MnSi/Ag epitaxial interfaces

Nedelkoski, Zlatko; Hasnip, Phil; Sanchez, Ana M.; Kuerbanjiang, Balati; Higgins, Edward; Oogane, Mikihiko; Hirohata, Atsufumi; Bell, Gavin R.; Lazarov, Vlado K.

doi:10.1063/1.4936630

Cited by 13 publications

(9 citation statements)

References 27 publications

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“…The change of the structure and chemistry at interfaces can significantly affect the spin-electronic structure locally14; for example the interface spin-polarisation can be reduced or reversed which leads to spin-scattering phenomena detrimental to the spin-injection efficiency into the semiconducting substrate. Hence determining the spin-polarisation at interfaces is important in designing optimal systems for applications.…”

Section: Resultsmentioning

confidence: 99%

Realisation of magnetically and atomically abrupt half-metal/semiconductor interface: Co2FeSi0.5Al0.5/Ge(111)

Nedelkoski

Kuerbanjiang

Glover

et al. 2016

Sci Rep

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Halfmetal-semiconductor interfaces are crucial for hybrid spintronic devices. Atomically sharp interfaces with high spin polarisation are required for efficient spin injection. In this work we show that thin film of half-metallic full Heusler alloy Co2FeSi0.5Al0.5 with uniform thickness and B2 ordering can form structurally abrupt interface with Ge(111). Atomic resolution energy dispersive X-ray spectroscopy reveals that there is a small outdiffusion of Ge into specific atomic planes of the Co2FeSi0.5Al0.5 film, limited to a very narrow 1 nm interface region. First-principles calculations show that this selective outdiffusion along the Fe-Si/Al atomic planes does not change the magnetic moment of the film up to the very interface. Polarized neutron reflectivity, x-ray reflectivity and aberration-corrected electron microscopy confirm that this interface is both magnetically and structurally abrupt. Finally, using first-principles calculations we show that this experimentally realised interface structure, terminated by Co-Ge bonds, preserves the high spin polarization at the Co2FeSi0.5Al0.5/Ge interface, hence can be used as a model to study spin injection from half-metals into semiconductors.

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Section: Resultsmentioning

confidence: 99%

Realisation of magnetically and atomically abrupt half-metal/semiconductor interface: Co2FeSi0.5Al0.5/Ge(111)

Nedelkoski

Kuerbanjiang

Glover

et al. 2016

Sci Rep

Self Cite

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“…It is known that the half-metallic nature of Heusler alloys at the interface can be sensitive to the exact configuration of the interface atoms, and this can affect the performance of the device. For example, it is known that Co 2 MnSi (CMS) grown on a silver surface changes significantly depending on whether it terminates with a Co layer or a Mn/Si layer [35]. For the CFAS/semiconductor interface, germanium provides an extremely good lattice match with only a 0.2% mismatch, compared to around 4.5% for CFAS/Si.…”

Section: Cfas/n-ge Interfacementioning

confidence: 99%

Simultaneous Prediction of the Magnetic and Crystal Structure of Materials Using a Genetic Algorithm

2019

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We introduce a number of extensions and enhancements to a genetic algorithm for crystal structure prediction, to make it suitable to study magnetic systems. The coupling between magnetic properties and crystal structure means that it is essential to take a holistic approach, and we present for the first time, a genetic algorithm that performs a simultaneous global optimisation of both magnetic structure and crystal structure. We first illustrate the power of this approach on a novel test system—the magnetic Lennard–Jones potential—which we define. Then we study the complex interface structures found at the junction of a Heusler alloy and a semiconductor substrate as found in a proposed spintronic device and show the impact of the magnetic interface structure on the device performance.

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“…the spatial extent of the diffusion can be limited to a very narrow interface region [16]. However, even for ideal half-metallic electrodes and atomically abrupt interfaces, DFT studies predict a reduction of the SP in the vicinity of the interface, as reported for Heusler/ GaAs and Heusler/Ag interfaces in [17][18][19]. In other words, structural and chemical abruptness of the interface does not necessarily lead to an interface electronic structure desirable for spintronic devices.…”

Section: Introductionmentioning

confidence: 99%

Controlling the half-metallicity of Heusler/Si(1 1 1) interfaces by a monolayer of Si–Co–Si

Nedelkoski

Kepaptsoglou

Ghasemi

et al. 2016

J. Phys.: Condens. Matter

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By using first-principles calculations we show that the spin-polarization reverses its sign at atomically abrupt interfaces between the half-metallic Co2(Fe,Mn)(Al,Si) and Si(1 1 1). This unfavourable spin-electronic configuration at the Fermi-level can be completely removed by introducing a Si–Co–Si monolayer at the interface. In addition, this interfacial monolayer shifts the Fermi-level from the valence band edge close to the conduction band edge of Si. We show that such a layer is energetically favourable to exist at the interface. This was further confirmed by direct observations of CoSi2 nano-islands at the interface, by employing atomic resolution scanning transmission electron microscopy.

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The effect of atomic structure on interface spin-polarization of half-metallic spin valves: Co2MnSi/Ag epitaxial interfaces

Cited by 13 publications

References 27 publications

Realisation of magnetically and atomically abrupt half-metal/semiconductor interface: Co2FeSi0.5Al0.5/Ge(111)

Realisation of magnetically and atomically abrupt half-metal/semiconductor interface: Co2FeSi0.5Al0.5/Ge(111)

Simultaneous Prediction of the Magnetic and Crystal Structure of Materials Using a Genetic Algorithm

Controlling the half-metallicity of Heusler/Si(1 1 1) interfaces by a monolayer of Si–Co–Si

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