Possible origin of nonlinear magnetic anisotropy variation in electric field effect in a double interface system

Yoshikawa, Daiji; Obata, Masao; Taguchi, Yasuhisa; Haraguchi, Shinya; Oda, Tetsuji

doi:10.7567/apex.7.113005

Cited by 13 publications

(11 citation statements)

References 30 publications

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“…could be related to the origin of the nonlinearity of the VCMA effect. Nonlinear VCMA effects were also reported in several systems in which the possible origins include electronic structures43, Rashba effect21, and strains44. The present temperature dependence in our experiment would provide a significant hint for future studies on the mechanisms of VCMA effects.…”

supporting

confidence: 66%

Voltage control of magnetic anisotropy in epitaxial Ru/Co2FeAl/MgO heterostructures

Wen

Sukegawa

Seki

et al. 2017

Sci Rep

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Voltage control of magnetic anisotropy (VCMA) in magnetic heterostructures is a key technology for achieving energy-efficiency electronic devices with ultralow power consumption. Here, we report the first demonstration of the VCMA effect in novel epitaxial Ru/Co2FeAl(CFA)/MgO heterostructures with interfacial perpendicular magnetic anisotropy (PMA). Perpendicularly magnetized tunnel junctions with the structure of Ru/CFA/MgO were fabricated and exhibited an effective voltage control on switching fields for the CFA free layer. Large VCMA coefficients of 108 and 139 fJ/Vm for the CFA film were achieved at room temperature and 4 K, respectively. The interfacial stability in the heterostructure was confirmed by repeating measurements. Temperature dependences of both the interfacial PMA and the VCMA effect were also investigated. It is found that the temperature dependences follow power laws of the saturation magnetization with an exponent of ~2, where the latter is definitely weaker than that of conventional Ta/CoFeB/MgO. The significant VCMA effect observed in this work indicates that the Ru/CFA/MgO heterostructure could be one of the promising candidates for spintronic devices with voltage control.

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supporting

confidence: 66%

Voltage control of magnetic anisotropy in epitaxial Ru/Co2FeAl/MgO heterostructures

Wen

Sukegawa

Seki

et al. 2017

Sci Rep

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“…In fact, interface resonant states (IRSs) are formed in the minority spin band of the Fe/MgO system, and the IRSs may affect the transport properties in the Fe/MgO-based MTJs, as proposed by Belashchenko et al [35]. The effect of IRSs on the VCMA at the Fe/MgO interface was also studied by means of ab initio calculations [36]. Thus, the results obtained are expected to contribute to the progress in theoretical studies, particularly in ab initio calculations [36][37][38][39][40][41], on the mechanism of VCMA.…”

Section: Resultsmentioning

confidence: 99%

Nonlinear electric field effect on perpendicular magnetic anisotropy in Fe/MgO interfaces

Xiang

Wen

Sukegawa

et al. 2017

J. Phys. D: Appl. Phys.

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The electric field effect on magnetic anisotropy was studied in an ultrathin Fe(001) monocrystalline layer sandwiched between Cr buffer and MgO tunnel barrier layers, mainly through post-annealing temperature and measurement temperature dependences. A large coefficient of the electric field effect of more than 200 fJ/Vm was observed in the negative range of electric field, as well as an areal energy density of perpendicular magnetic anisotropy (PMA) of around 600 J/m 2 . More interestingly, nonlinear behavior, giving rise to a local minimum around +100 mV/nm, was observed in the electric field dependence of magnetic anisotropy, being independent of the post-annealing and measurement temperatures. The insensitivity to both the interface conditions and the temperature of the system suggests that the nonlinear behavior is attributed to an intrinsic origin such as an inherent electronic structure in the Fe/MgO interface. The present study can contribute to the progress in theoretical studies, such as ab initio calculations, on the mechanism of the electric field effect on PMA. 5 Corresponding author

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“…It is well known that localized surface states are formed at the Fe=MgO interface [56]. The first principle calculations predict that the localized surface states may act as intrinsic charge-trapping sites and make the reverse point of the VCMA effect [57]. The VCMA contribution due to the localized surface states may change its polarity depending on the energy of the localized states.…”

Section: Voltage Control Of Magnetic Anisotropymentioning

confidence: 99%

Large Voltage-Induced Changes in the Perpendicular Magnetic Anisotropy of an MgO-Based Tunnel Junction with an Ultrathin Fe Layer

et al. 2016

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We study the voltage control of perpendicular magnetic anisotropy in an ultrathin Fe layer sandwiched between the Cr buffer and MgO tunneling barrier layers. A high-interface magnetic anisotropy energy of 2.1 mJ=m 2 is achieved in the Cr/ultrathin Fe=MgO structure. A large voltage-induced perpendicular magnetic anisotropy change is observed under the negative-bias voltage applications for the case of the Fe layer thinner than 0.6 nm. The amplitude of the voltage-induced anisotropy energy change exhibits a strong Fe-thickness dependence and it reaches as high as 290 fJ=Vm. The observed high values of the surface anisotropy and voltage-induced anisotropy energy change demonstrate the feasibility of voltage-driven spintronic devices.

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Possible origin of nonlinear magnetic anisotropy variation in electric field effect in a double interface system

Cited by 13 publications

References 30 publications

Voltage control of magnetic anisotropy in epitaxial Ru/Co2FeAl/MgO heterostructures

Voltage control of magnetic anisotropy in epitaxial Ru/Co2FeAl/MgO heterostructures

Nonlinear electric field effect on perpendicular magnetic anisotropy in Fe/MgO interfaces

Large Voltage-Induced Changes in the Perpendicular Magnetic Anisotropy of an MgO-Based Tunnel Junction with an Ultrathin Fe Layer

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