Shingo Tamaru

National Institute of Advanced Industrial Science and Technology

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Hitoshi Kubota

Kyocera (United States)

Shinji Yuasa

National Institute of Advanced Industrial Science and Technology

Kay Yakushiji

National Institute of Advanced Industrial Science and Technology

Akio Fukushima

National Institute of Advanced Industrial Science and Technology

Takayuki Nozaki

National Institute of Advanced Industrial Science and Technology

Tatsuya Yamamoto

National Institute of Advanced Industrial Science and Technology

Yoshishige Suzuki

Osaka University

Hiroshi Imamura

National Institute of Advanced Industrial Science and Technology

Yoichi Shiota

Spintronics Research Network of Japan

Sumito Tsunegi

National Institute of Advanced Industrial Science and Technology

Cooperative Institutions

Tohoku University

National Institute of Advanced Industrial Science and Technology

Spintronics Research Network of Japan

National Institute for Materials Science

Osaka University

The University of Tokyo

Japan Science and Technology Agency

Nagoya University

Advanced Institute of Materials Science

University of Tsukuba

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Low Gilbert damping in epitaxial thin films of the nodal-line semimetal D03−Fe3Ga

Physical review. B./Physical review. B (2021)

Shoya Sakamoto Tomoya Higo Shingo Tamaru Hitoshi Kubota Kay Yakushiji

$D{0}_{3}$-ordered ${\mathrm{Fe}}_{3}\mathrm{Ga}$ has been recently reported to show a giant anomalous Nernst effect due to a large Berry curvature along the interconnected nodal lines concentrated near the Fermi level. This peculiar band structure may be advantageous for spintronics device applications because one can expect a strong response to a gate-voltage application. This study evaluates the Gilbert damping constants, a key parameter governing the magnetization dynamics of epitaxial thin films of $D{0}_{3}\text{\ensuremath{-}}{\mathrm{Fe}}_{3}\mathrm{Ga}$ and bcc-Fe by ferromagnetic resonance measurements. We find that the Gilbert damping constant of $D{0}_{3}\text{\ensuremath{-}}{\mathrm{Fe}}_{3}\mathrm{Ga} [(6.0\ifmmode\pm\else\textpm\fi{}0.2)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}]$ is relatively low and comparable to that of Fe $[(2.3\ifmmode\pm\else\textpm\fi{}0.2)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}]$. The low Gilbert damping suggests that the interconnected nodal lines near the Fermi level do not hinder magnetization dynamics, making $D{0}_{3}\text{\ensuremath{-}}{\mathrm{Fe}}_{3}\mathrm{Ga}$ even more attractive as a building block of spintronics devices.

10.1103/physrevb.103.165122

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Citations (6)

The Chiral Splitting of Spin Wave Eigen Modes in the 120-nm-radius FeB Disk Shaped Nano-magnet

Extended Abstracts of the 2020 International Conference on Solid State Devices and Materials (2016)

J. Cho Shinji Miwa Kay Yakushiji Shingo Tamaru Hitoshi Kubota

10.7567/ssdm.2016.g-1-04

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Stability of out-of-plane precession with the application of a tilted magnetic field in spin torque oscillator having a planar free layer and a perpendicular polarizer

The Japan Society of Applied Physics (2016)

Ryo Hiramatsu Hitoshi Kubota Sumito Tsunegi Shingo Tamaru Kay Yakushiji

Polarizer

Precession

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Magneto-transport properties in perpendicularly magnetized magnetic tunnel junctions using an Mg40Fe10O50 tunnel barrier

Acta Materialia (2024)

Tatsuya Yamamoto Tomohiro Ichinose Jun Uzuhashi Takayuki Nozaki T. Ohkubo

Tunnel magnetoresistance

Magneto

Tunnel junction

10.1016/j.actamat.2024.119749

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Large voltage-induced magnetic anisotropy change in Cr/ultrathin Fe/MgO/Fe magnetic tunnel junctions II

The Japan Society of Applied Physics (2016)

Takayuki Nozaki A. Kozioł‐Rachwał Witold Skowroński Vadym Zayets Yoichi Shiota

Tunnel magnetoresistance

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Size dependence of oscillation characteristic in Spin Torque Oscillators

The Japan Society of Applied Physics (2016)

K. Mizunuma Yasushi Kono Yoshihiko Isobe Hiroyuki Wado Bochong Wang

Oscillation (cell signaling)

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Interfacial enhancement of g -factor at CoFeB/MgO characterized by a high sensitivity ferromagnetic resonance spectroscopy

The Japan Society of Applied Physics (2021)

Tatsuya Yamamoto Shingo Tamaru Takayuki Nozaki Kay Yakushiji Hitoshi Kubota

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Cryogenic Temperature Deposition of High-Performance CoFeB/MgO/CoFeB Magnetic Tunnel Junctions on ϕ300 mm Wafers

ACS Applied Electronic Materials (2023)

Tomohiro Ichinose Tatsuya Yamamoto Takayuki Nozaki Kay Yakushiji Shingo Tamaru

We developed a cryogenic temperature deposition process for high-performance CoFeB/MgO/CoFeB magnetic tunnel junctions (MTJs) on ϕ300 mm thermally oxidized silicon wafers. The effect of the deposition temperature of the CoFeB layers on the nanostructure, magnetic, and magneto-transport properties of the MTJs was investigated in detail. When CoFeB was deposited at 100 K, the MTJs exhibited a perpendicular magnetic anisotropy (PMA) of 214 μJ/m2 and a voltage-controlled magnetic anisotropy (VCMA) coefficient of −45 fJ/V m, corresponding to 1.4- and 1.7-fold enhancements in PMA and VCMA, respectively, compared to the case of room-temperature deposition of CoFeB. The improvement in the MTJ properties was not simply due to the morphology of the MTJ films. The interface-sensitive magneto-transport properties indicated that interfacial qualities such as intermixing and oxidation states at the MgO/CoFeB interfaces were improved by the cryogenic temperature deposition. A cryogenic temperature sputtering deposition is expected to be a standard manufacturing process for next-generation magnetoresistive random-access memory.

Tunnel magnetoresistance

Deposition

10.1021/acsaelm.3c00068

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Citations (7)

Magnetization switching assisted by high-frequency-voltage-induced ferromagnetic resonance

Applied Physics Express (2014)

Takayuki Nozaki Hiroko Arai Kay Yakushiji Shingo Tamaru Hitoshi Kubota

Magnetization switching assisted by high-frequency voltage was demonstrated in magnetic tunnel junctions with perpendicular magnetization. Ferromagnetic resonance was excited by high-frequency voltage instead of by a high-frequency magnetic field. A frequency-dependent reduction in the switching field (coercive force) was clearly observed with a maximum reduction rate of more than 80% under a radio-frequency power application of 3 dBm. The developed technique can provide a novel approach to energy-assisted magnetization switching with low ohmic dissipation.

10.7567/apex.7.073002

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Citations (30)

Diameter dependence of emission power in MgO-based nano-pillar spin-torque oscillators

Applied Physics Letters (2016)

Bochong Wang Hitoshi Kubota Kay Yakushiji Shingo Tamaru Hiroko Arai

The dependence on diameter of the emission power in MgO-based nano-pillar spin torque oscillators (STOs) was systematically investigated. A maximum emission power of over 2.5 μW was obtained around 300 nm in diameter, which is the largest reported to date among the out-of-plane precession STOs. By analyzing physical quantities, precession cone angle of the free-layer magnetization was evaluated. In the diameter range below 300 nm, the increase in power was mainly due to the increase of the injected current. The power decrease above 300 nm is possibly attributed to the decrease in the averaged precession cone angle, suggesting spatial phase difference of magnetization precession. This study provides the method for estimating the optimum STO diameter, which is of great importance in practical use.

Precession

Ligand cone angle

10.1063/1.4954760

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Citations (13)