Size Dependence of Magnetic Properties of Nanoscale CoFeB–MgO Magnetic Tunnel Junctions with Perpendicular Magnetic Easy Axis Observed by Ferromagnetic Resonance

Mizunuma, K.; Yamanouchi, Michihiko; Sato, Hideo; Ikeda, Shoji; Kanai, Shun; Matsukura, F.; Ohno, Hideo

doi:10.7567/apex.6.063002

Cited by 42 publications

(27 citation statements)

References 45 publications

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“…The FMR spectrum of free CoFeB layer (Fig. 2(d)) can be fitted by linear combination of symmetric and anti-symmetric Lorentzian functions given by refs 18, 32, 33:where, V s and V as are the amplitudes of symmetric and anti-symmetric terms, σ is the half width at half maximum (HWHM) of the spectrum and f FMR is the FMR frequency. For homodyne-detected signal, V s originates from STT induced FMR, whereas V as originates from the FMR induced by VCMA torque and/or FLT 18, 33, 34 .…”

Section: Resultsmentioning

confidence: 99%

Effect of excitation power on voltage induced local magnetization dynamics in an ultrathin CoFeB film

Rana

Fukuma

Miura

et al. 2017

Sci Rep

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Voltage or electric field induced magnetization dynamics promises low power spintronics devices. For successful operation of some spintronics devices such as magnetic oscillators and magnetization switching devices a clear understanding of nonlinear magnetization dynamics is required. Here, we report a detailed experimental and micromagnetic simulation study about the effect of excitation power on voltage induced local magnetization dynamics in an ultrathin CoFeB film. Experimental results show that the resonance line-width and frequency remains constant, whereas cone angle of the magnetization precession increases linearly with square-root of excitation power below threshold value, known as linear excitation regime. Above threshold power, the dynamics enters into nonlinear regime where resonance line-width monotonically increases and resonance frequency monotonically decreases with increasing excitation power. Simulation results reveal that a strong nonlinear and incoherent magnetization dynamics are observed in our experiment above the threshold power which reduces dynamic magnetic signal by suppressing large cone angle of magnetization precession. Moreover, a significant transfer of spin angular momentum from uniform FMR mode to its degenerate spin waves outside of excitation area further restrict the cone angle of precession within only few degrees in our device. Our results will be very useful to develop all-voltage-controlled spintronics devices.

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Section: Resultsmentioning

confidence: 99%

Effect of excitation power on voltage induced local magnetization dynamics in an ultrathin CoFeB film

Rana

Fukuma

Miura

et al. 2017

Sci Rep

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“…In this work, the resonance was measured by a homodyne detection technique. The electric-field-induced ferromagnetic resonance is an important tool for evaluating the magnetic properties of nanoscale spintronic devices 59 .…”

Section: Electrical Control Of Magnetization In Magnetic Metalsmentioning

confidence: 99%

Control of magnetism by electric fields

2015

Self Cite

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The electrical manipulation of magnetism and magnetic properties has been achieved across a number of different material systems. For example, applying an electric field to a ferromagnetic material through an insulator alters its charge-carrier population. In the case of thin films of ferromagnetic semiconductors, this change in carrier density in turn affects the magnetic exchange interaction and magnetic anisotropy; in ferromagnetic metals, it instead changes the Fermi level position at the interface that governs the magnetic anisotropy of the metal. In multiferroics, an applied electric field couples with the magnetization through electrical polarization. This Review summarizes the experimental progress made in the electrical manipulation of magnetization in such materials, discusses our current understanding of the mechanisms, and finally presents the future prospects of the field.

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“…The experimental values of 2 = eff 1 are 0.19 for FeB 24) and 0.098 for CoFeB. 25) These values are in the admissible range for self-oscillation. The ratio for these materials is, however, still too small to realize zero-field oscillation in a wide current range, as shown in Fig.…”

mentioning

confidence: 80%

Spin-torque-induced oscillation at zero bias field in a magnetoresistive nanopillar with a free layer with first- and second-order uniaxial anisotropy

Arai

Matsumoto

Yuasa

et al. 2015

Appl. Phys. Express

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Spin-torque-induced magnetization dynamics in a nanopillar having a perpendicularly magnetized free layer with firstand second-order uniaxial anisotropy and an in-plane magnetized reference layer is studied theoretically on the basis of the macrospin model. It is shown that in the presence of second-order uniaxial anisotropy, self-oscillation is induced even at zero bias magnetic field. Analytical expressions for the threshold current, condition of the second-order anisotropy constant required for oscillation, and current dependence of the oscillation frequency are obtained.

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Size Dependence of Magnetic Properties of Nanoscale CoFeB–MgO Magnetic Tunnel Junctions with Perpendicular Magnetic Easy Axis Observed by Ferromagnetic Resonance

Cited by 42 publications

References 45 publications

Effect of excitation power on voltage induced local magnetization dynamics in an ultrathin CoFeB film

Effect of excitation power on voltage induced local magnetization dynamics in an ultrathin CoFeB film

Control of magnetism by electric fields

Spin-torque-induced oscillation at zero bias field in a magnetoresistive nanopillar with a free layer with first- and second-order uniaxial anisotropy

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