Interface resonance in Fe/Pt/MgO multilayer structure with large voltage controlled magnetic anisotropy change

Jibiki, Yuma; Goto, Minori; Tsujikawa, Motokazu; Risius, Philipp; Hasebe, Shigeru; Xu, Xiandong; Nawaoka, Kohei; Ohkubo, T.; Hono, K.; Shirai, Masamitsu; Miwa, Shinji; Suzuki, Y.

doi:10.1063/1.5082254

Cited by 10 publications

(5 citation statements)

References 38 publications

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“…We employed the molecular beam epitaxy (MBE) method to fabricate the V/Fe/MgO trilayer on an MgO (001) single-crystalline substrate (Figure a). , Prior to the deposition, we annealed the substrate at 800 °C for 10 min. A 5 nm thick MgO seed layer was first grown at a rate of 0.1 Å/s.…”

Section: Methodsmentioning

confidence: 99%

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Electron Correlation Enhances Orbital Polarization at a Ferromagnetic Metal/Insulator Interface: Depth-Resolved X-ray Magnetic Circular Dichroism and First-Principles Study

Sakamoto

Tsujikawa

Shirai

et al. 2022

ACS Appl. Electron. Mater.

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The Fe(CoB)/MgO interface is vital to spintronics as it exhibits the tunneling magnetoresistance (TMR) effect and interfacial perpendicular magnetic anisotropy (PMA) simultaneously. To further enhance TMR and PMA for the development of high-density magnetoresistive random access memory, it is essential to clarify the behavior of Fe atoms interfaced with MgO. This study reveals that the spin and orbital magnetic moments of Fe are enhanced at the Fe/MgO interface. The enhancement in the orbital magnetic moment is much more significant than that predicted by the standard density functional theory. Theoretical calculations based on the orbital polarization correction reproduce this enhancement, the origin of which is attributed to the electron−electron correlation resulting from electron localization at the Fe/MgO interface. The present findings highlight the importance of electron−electron correlation at ferromagnet/oxide interfaces, which has often been disregarded in spintronics.

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Section: Methodsmentioning

confidence: 99%

“…An Fe layer (0.7 nm, 5 ML) and MgO overlayer (2 nm) were deposited at rates of 0.05 and 0.1 Å/s, respectively. A V buffer layer was employed to induce PMA at the Fe/MgO interface , and to achieve atomically flat interfaces with minimal lattice defects . All the depositions were conducted at room temperature.…”

Section: Methodsmentioning

confidence: 99%

Electron Correlation Enhances Orbital Polarization at a Ferromagnetic Metal/Insulator Interface: Depth-Resolved X-ray Magnetic Circular Dichroism and First-Principles Study

Sakamoto

Tsujikawa

Shirai

et al. 2022

ACS Appl. Electron. Mater.

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“…Recent studies also reported an improved VCMA effect in Fe/Pt/MgO or CoFe/Ir/MgO structures by inserting an ultrathin HM layer of Pt or Ir at the FM/oxide interface. [ 51–53 ] This was explained by the modification of the interfacial electronic states of the FM near the Fermi level by the introduction of those materials with strong spin‐orbit coupling. There is another possibility that the inserted Pt layer could serve as a catalyst to facilitate oxygen ion migration.…”

Section: Resultsmentioning

confidence: 99%

Reduced Spin‐Orbit Torque Switching Current by Voltage‐Controlled Easy‐Cone States

Jeong

Kang

Lee

et al. 2021

Adv Funct Materials

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Spin‐orbit torque (SOT) promises fast and reliable switching of the perpendicular magnetization in spintronic devices, such as magnetic random‐access memory or spin logic devices. To apply the SOT technology to practical devices with low power consumption, it is necessary to reduce the switching current. To this end, most of the research to date in this area has focused on improving the charge‐to‐spin conversion efficiency in heavy metal/ferromagnet structures. In this study, it is reported that the SOT switching current is significantly reduced by modulating magnetic easy‐cone states through voltage‐controlled magnetic anisotropy (VCMA). The introduction of a thin Pt layer at the CoFeB/MgO interface enhances the VCMA effect, allowing a magnetic easy‐cone state of CoFeB to be formed and controlled by the gate voltage. As a result, the SOT switching current density is reduced by up to 50% when the easy‐cone angle is changed from 0° to 58°. Furthermore, the magnetic easy‐cone state is gradually modulated in a reversible and non‐volatile manner, facilitating multilevel spintronic devices.

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“…For the macrospin simulations, we considered a ferromagnetic disk of thickness t = 0.9 nm, saturation magnetization M s = 1000 kA/m and an out-of-plane effective anisotropy field of µ 0 H K = 80 mT. These parameters are rather usual values for ferromagnetic thin films exhibiting perpendicular magnetic anisotropy (PMA) 29 , 30 and particularly, they are typical for heavy-metal/ferromagnet/oxide systems most common in VCMA studies 14 , 21 , 31 , 32 . This model satisfies magnetic entities with lateral dimensions bellow the domain wall width, which in this case is around 72 nm.…”

Section: Resultsmentioning

confidence: 99%

Route towards efficient magnetization reversal driven by voltage control of magnetic anisotropy

One

Béa

Mican

et al. 2021

Sci Rep

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The voltage controlled magnetic anisotropy (VCMA) becomes a subject of major interest for spintronics due to its promising potential outcome: fast magnetization manipulation in magnetoresistive random access memories with enhanced storage density and very low power consumption. Using a macrospin approach, we carried out a thorough analysis of the role of the VCMA on the magnetization dynamics of nanostructures with out-of-plane magnetic anisotropy. Diagrams of the magnetization switching have been computed depending on the material and experiment parameters (surface anisotropy, Gilbert damping, duration/amplitude of electric and magnetic field pulses) thus allowing predictive sets of parameters for optimum switching experiments. Two characteristic times of the trajectory of the magnetization were analyzed analytically and numerically setting a lower limit for the duration of the pulses. An interesting switching regime has been identified where the precessional reversal of magnetization does not depend on the voltage pulse duration. This represents a promising path for the magnetization control by VCMA with enhanced versatility.

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Interface resonance in Fe/Pt/MgO multilayer structure with large voltage controlled magnetic anisotropy change

Cited by 10 publications

References 38 publications

Electron Correlation Enhances Orbital Polarization at a Ferromagnetic Metal/Insulator Interface: Depth-Resolved X-ray Magnetic Circular Dichroism and First-Principles Study

Electron Correlation Enhances Orbital Polarization at a Ferromagnetic Metal/Insulator Interface: Depth-Resolved X-ray Magnetic Circular Dichroism and First-Principles Study

Reduced Spin‐Orbit Torque Switching Current by Voltage‐Controlled Easy‐Cone States

Route towards efficient magnetization reversal driven by voltage control of magnetic anisotropy

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