Large Sign Reversal of Tunneling Magnetoresistance in an Epitaxial Fe/MgAlOx/Fe4N Magnetic Tunnel Junction

Ma, Tianyi; Zhu, Yu; Dainone, Pambiang Abel; Chen, Tongxin; Devaux, Xavier; Wan, Caihua; Migot, Sylvie; Lengaigne, Gwladys; Vergnat, Michel; Yan, Yu; Han, Xiufeng; Lu, Yuan

doi:10.1021/acsaelm.3c00937

Cited by 3 publications

(1 citation statement)

References 50 publications

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“…Transport properties serve as a crucial tool to understand the scattering mechanisms in the two-dimensional electron gas (2DEG) channel effectively. Various characterization techniques have been employed to ensure the production of high-quality samples. − Magnetoresistance measurements in quantum transport serve as a powerful tool for characterizing compound semiconductors, facilitating a deeper understanding of their electronic properties. − Quantum oscillations and their scattering phenomena have been extensively explored in various GaN based heterostructures. ,,− However, the quantum transport behaviors in this high-mobility InAlN/GaN heterostructure have not been widely reported. In particular, study on the InAlN/GaN 2DEG systems with high mobility remains a long-standing challenge due to growth challenges.…”

Section: Introductionmentioning

confidence: 99%

Enhanced Shubnikov–de Haas Oscillations in High Mobility InAlN/GaN Two-Dimensional Electron Gas

Karmakar,

Kaneriya,

Mukherjee

et al. 2024

ACS Appl. Electron. Mater.

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A high-quality In 0.17 Al 0.83 N/GaN heterostructure with a record high mobility of 11370 cm 2 V −1 s −1 is achieved at 2 K using the metal oxide chemical vapor deposition (MOCVD) technique, where enhanced Shubnikov−de Haas (SdH) oscillations of two-dimensional electron gas (2DEG) are observed at low temperatures up to 20 K. In this study, we explore the quantum transport properties induced by 2DEG using perpendicular magnetic (B ⊥ ) field strengths up to 14 T. Excellent crystalline and structural quality of the ultrathin InAlN/GaN heterostructure was revealed by high resolution X-ray diffraction (HRXRD) and high-angle annular dark-field (HAADF) scanning transmission electron microscopy (STEM). From the temperature-dependent oscillation amplitude, we have derived effective mass m* ≈ 0.247m e . Furthermore, the dominance of small-angle scattering in the 2DEG channel is evidenced by a quantum lifetime (τ q ) to Hall transport lifetime (τ t ) ratio of less than unity (τ q /τ t ≪ 1). These findings offer a robust foundation for exploration into fundamental physics and emergent phenomena in quantum transport within the InAlN/GaN 2DEG, leading to better suitability and a way forward to high power−high frequency GaN high electron mobility transistor (HEMT) development.

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Section: Introductionmentioning

confidence: 99%

Enhanced Shubnikov–de Haas Oscillations in High Mobility InAlN/GaN Two-Dimensional Electron Gas

Karmakar,

Kaneriya,

Mukherjee

et al. 2024

ACS Appl. Electron. Mater.

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Impact of Interfacial Disorder and Band Structure on the Resonant Conductance Oscillation in Quantum-Well-Based Magnetic Tunnel Junctions

Ma,

Tao,

Devaux

et al. 2024

ACS Appl. Electron. Mater.

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Quantum well (QW) states formed in a double-barrier magnetic tunnel junction (DMTJ) enable the coherent resonant tunneling of electrons. This phenomenon is significant for both the fundamental understanding of quantum transport and the development of advanced functionalities in spintronic devices. Careful engineering of the structural and chemical disorders at the QW/barrier interface is essential to maintain strong electron phase coherence, thereby ensuring reliable conductance oscillations in DMTJ. In this study, we systematically investigate the influence of interfacial disorders and band structure on QW-induced conductance oscillations in epitaxial Fe/MgAlO x /Fe (QW)/MgAlO x /Co/ Fe DMTJs grown by molecular beam epitaxy. It is found that the amplitude of QW oscillations is reduced to one-third due to chemical disorders caused by the incorporation of 2−4 monolayers of Co at the Fe (QW)/MgAlO x interface. In contrast, structural disorder induced by the incorporation of a single Fe monolayer completely suppresses the oscillations. In addition, the QW oscillation depends on the available majority Δ 1 states of the injecting electrons at the Fermi level (E F ) with k // = 0 from the upper electrode. Replacing the Fe upper electrode with Fe 4 N, which lacks a majority of Δ 1 states at E F , significantly reduces the oscillation amplitude. Instead, using the bcc Co upper electrode, which possesses majority Δ 1 states, results in no change in QW oscillation. Our findings highlight the critical role of interfacial disorder and band structure in QW-induced conductance oscillations, advancing the development of spin-dependent quantum resonant tunneling applications.

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Epitaxial Au/Fe4N/MgO thin films on GaAs (001) substrates

Dainone,

Stoffel,

Chen

et al. 2024

Journal of Applied Physics

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We investigate the growth of Au/FexNy/MgO trilayers on GaAs(001) substrates by plasma-assisted molecular beam epitaxy. The optimization of the growth conditions made it possible to obtain the compound of stoichiometric Fe4N. Microstructural studies show that Fe4N forms 3D islands at the initial stages of growth. As the Fe4N thickness increases, a columnar growth sets in leading to a strong texturing and to the formation of grains having the same crystallographic orientation. The growth is epitaxial with the relationship GaAs (001) [110]//MgO (001) [110]//Fe4N (001) [110]//Au (012) [0–32]. A chemical analysis at the nanoscale reveals that the interfaces are rather sharp with a limited interdiffusion. Magnetic characterizations show that a trilayer containing a 1-nm-thick Fe4N layer is already ferromagnetic. The easy magnetization axis is in-plane independent of the Fe4N layer thickness (from 1 to 6 nm). This study shows the potential to use Fe4N as a spin injector for spin-optoelectronic applications.

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Large Sign Reversal of Tunneling Magnetoresistance in an Epitaxial Fe/MgAlO_x/Fe₄N Magnetic Tunnel Junction

Cited by 3 publications

References 50 publications

Enhanced Shubnikov–de Haas Oscillations in High Mobility InAlN/GaN Two-Dimensional Electron Gas

Enhanced Shubnikov–de Haas Oscillations in High Mobility InAlN/GaN Two-Dimensional Electron Gas

Impact of Interfacial Disorder and Band Structure on the Resonant Conductance Oscillation in Quantum-Well-Based Magnetic Tunnel Junctions

Epitaxial Au/Fe4N/MgO thin films on GaAs (001) substrates

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