Electric field control of magnetic anisotropy in the easy cone state of Ta/Pt/CoFeB/MgO structures

Park, Kyung-Woong; Park, Juneyoung; Baek, Seung-heon Chris; Kim, Dae-Hoon; Seo, Soo Hong; Chung, Sungkwon; Park, Byong‐Guk

doi:10.1063/1.4955451

Cited by 28 publications

(12 citation statements)

References 37 publications

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“…Matsumoto et al proposed using a combination of a conical magnetization state and shape anisotropy to induce precessional switching under zero-bias magnetic field [146]. Conical magnetization states have been mainly studied in multilayer structures containing Co, such as Co/Pt and Co/Pd [147,148,149], however recently it can be realized, even in a practical CoFeB/MgO structure [150,151,152]. Therefore, the above proposed structure might be applicable if we can realize a sufficiently-high thermal stability while keeping the conical states.…”

Section: Towards Reliable Voltage-induced Dynamic Switchingmentioning

confidence: 99%

Recent Progress in the Voltage-Controlled Magnetic Anisotropy Effect and the Challenges Faced in Developing Voltage-Torque MRAM

et al. 2019

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The electron spin degree of freedom can provide the functionality of “nonvolatility” in electronic devices. For example, magnetoresistive random access memory (MRAM) is expected as an ideal nonvolatile working memory, with high speed response, high write endurance, and good compatibility with complementary metal-oxide-semiconductor (CMOS) technologies. However, a challenging technical issue is to reduce the operating power. With the present technology, an electrical current is required to control the direction and dynamics of the spin. This consumes high energy when compared with electric-field controlled devices, such as those that are used in the semiconductor industry. A novel approach to overcome this problem is to use the voltage-controlled magnetic anisotropy (VCMA) effect, which draws attention to the development of a new type of MRAM that is controlled by voltage (voltage-torque MRAM). This paper reviews recent progress in experimental demonstrations of the VCMA effect. First, we present an overview of the early experimental observations of the VCMA effect in all-solid state devices, and follow this with an introduction of the concept of the voltage-induced dynamic switching technique. Subsequently, we describe recent progress in understanding of physical origin of the VCMA effect. Finally, new materials research to realize a highly-efficient VCMA effect and the verification of reliable voltage-induced dynamic switching with a low write error rate are introduced, followed by a discussion of the technical challenges that will be encountered in the future development of voltage-torque MRAM.

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Section: Towards Reliable Voltage-induced Dynamic Switchingmentioning

confidence: 99%

Recent Progress in the Voltage-Controlled Magnetic Anisotropy Effect and the Challenges Faced in Developing Voltage-Torque MRAM

et al. 2019

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“…SIII [42] and Refs. [23,[63][64][65][66][67][68][69][70][71], we first discuss our measurement methodology, and a commonly used model for analyzing the data (the Ellipse Model, see Sec. SIII.A), which arises from a basic understanding of magnetic anisotropy.…”

Section: Vcma In Stoࢨco(pt)ࢨptmentioning

confidence: 99%

Electronic voltage control of magnetic anisotropy at room temperature in high- κ SrTiO3/Co/Pt trilayer

Vermeulen

Swerts

Couet

et al. 2020

Phys. Rev. Materials

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To improve power efficiency and endurance of magnetic memory technologies, a voltage-controlled mechanism is desirable. The voltage control of magnetic anisotropy (VCMA) effect in MgO stacks is a promising option, however, its strength is too low for memory applications. Replacing the standard MgO layer by an oxide with a higher permittivity κ may help improve the VCMA strength. We demonstrate a VCMA effect up to ξ = 75 fJ/Vm at room temperature in a CoࢨPt bilayer grown on atomic layer deposited (ALD) high-κ SrTiO 3 (STO). After treating the STO surface with isopropanol, a thin CoO x interfacial layer is observed, enabling VCMA. Upon cooling down from room temperature to 200 K, the VCMA effect strength increases by a factor of two. This increase is incompatible with the expected Arrhenius temperature dependence for an ionic effect and thus we argue that the observed VCMA effect is electronic. Electronic VCMA is desirable for adequate memory endurance, and hence the approach proposed here has great potential for applications.

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“…Here, we applied a 𝑉 : to the top electrode for 5 minutes at 150 ℃ and then measured 𝑅 8 at room temperature. This is possible because the voltage effect is maintained even after turning off the 𝑉 : [31,32,41,42]. The result shows that the PMA is gradually weakened by positive 𝑉 : 's and restored by subsequent negative 𝑉 : 's, indicating that the PMA in our Co/Ni multilayer sample is effectively modulated by 𝑉 : .…”

Section: Voltage-controlled Perpendicular Magnetic Anisotropymentioning

confidence: 82%

Voltage-driven gigahertz frequency tuning of spin Hall nano-oscillators

Choi

Park

Kang

et al. 2021

Preprint

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Spin Hall nano-oscillators (SHNOs) exploiting current-driven magnetization auto-oscillation have recently received much attention because of their potential for oscillator-based neuromorphic computing. Widespread neuromorphic application with SHNOs requires an energy-efficient way to tune oscillation frequency in broad ranges and store trained frequencies in SHNOs without the need for additional memory circuitry. Voltage control of oscillation frequency of SHNOs was experimentally demonstrated, but the voltage-driven frequency tuning was volatile and limited to megahertz ranges. Here, we show that the frequency of SHNO is controlled up to 2.1 GHz by a moderate electric field of 1.25 MV/cm. The large frequency tuning is attributed to the voltage-controlled magnetic anisotropy (VCMA) in a perpendicularly magnetized Ta/Pt/[Co/Ni]n/Co/AlOx structure. Moreover, non-volatile VCMA effect enables control of the cumulative frequency using repetitive voltage pulses, which mimic the potentiation and depression functions of biological synapses. Our results suggest that the voltage-driven frequency tuning of SHNOs facilitates the development of energy-efficient spin-based neuromorphic devices.

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Electric field control of magnetic anisotropy in the easy cone state of Ta/Pt/CoFeB/MgO structures

Cited by 28 publications

References 37 publications

Recent Progress in the Voltage-Controlled Magnetic Anisotropy Effect and the Challenges Faced in Developing Voltage-Torque MRAM

Recent Progress in the Voltage-Controlled Magnetic Anisotropy Effect and the Challenges Faced in Developing Voltage-Torque MRAM

Electronic voltage control of magnetic anisotropy at room temperature in high- κ SrTiO3/Co/Pt trilayer

Voltage-driven gigahertz frequency tuning of spin Hall nano-oscillators

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