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

Nozaki, Takayuki; Kozioł–Rachwał, A.; Skowroński, Witold; Zayets, V.; Shiota, Yoichi; Tamaru, Shingo; Kubota, Hiroshi; Fukushima, Akio; Yuasa, Shinji; Suzuki, Y.

doi:10.1103/physrevapplied.5.044006

Cited by 154 publications

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“…The following discussion assumes an effective magnetic dead layer (t d ) with a thickness of 0.09 nm, which can be estimated from the nominal Fe thickness dependence of the magnetic moment (see Supplementary Information S4). The existence of the t d is mainly attributed to intermixing at the Cr/Fe interface; 36,37 we observed no clear changes in the t d with changes in the inserted Ir thickness. Figure 3a shows the t Ir dependence of the saturation magnetization (M S ) for a fixed t Fe = 1.0 nm.…”

Section: Resultsmentioning

confidence: 49%

“…This value is~1.8 times greater than that observed in the pure/MgO interface (2.0 mJ m − 2 ). 35,36 Further doping of Ir leads to a reduction in this value; however, even at t Ir = 0.15 nm, the K i,0 value is still greater than that for the sample without Ir doping. It should be emphasized that no PMA was observed at the Cr/Ir-doped Fe interface (see Supplementary Information S6), similar to the Cr/Fe structure.…”

Section: Resultsmentioning

confidence: 87%

“…For comparison, data for the Cr/Fe/MgO structure (open black circles) are also shown in the same graph. 36 The K eff t total values (red crosses) evaluated from the magneto-optic Kerr effect hysteresis loops in the thinner Fe ranges for t Ir = 0.05 nm are shown here as well. Positive K eff t total values indicate the out-of-plane magnetic easy axis.…”

Section: Resultsmentioning

confidence: 99%

“…It should be emphasized that no PMA was observed at the Cr/Ir-doped Fe interface (see Supplementary Information S6), similar to the Cr/Fe structure. 36 Therefore, the observed large K i,0 value mainly comes from the top Ir-doped Fe/MgO single interface. Figure 4b shows the layer-resolved MAE for each structure.…”

Section: Resultsmentioning

confidence: 99%

“…As shown in Figure 2a, we noted PMA in the t Fe range from 0.5 to 0.9 nm for Cr/Fe/MgO; this result is attributed to Fe/MgO interfacial anisotropy. 35,36 The critical thickness of Fe, for which a spin reorientation transition (SRT) from the out-ofplane to in-plane direction occurs, was determined to be 0.9 nm. The Ir doping in the ultrathin Fe layer has a distinct influence on the First, zero-remanence loops for the polar configuration were noted for very thin Fe layers, which indicates that in-plane anisotropy dominates for very thin Fe layers (see also Supplementary Information S3).…”

Section: Resultsmentioning

confidence: 99%

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Highly efficient voltage control of spin and enhanced interfacial perpendicular magnetic anisotropy in iridium-doped Fe/MgO magnetic tunnel junctions

et al. 2017

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Voltage control of spin enables both a zero standby power and ultralow active power consumption in spintronic devices, such as magnetoresistive random-access memory devices. A practical approach to achieve voltage control is the electrical modulation of the spin-orbit interaction at the interface between 3d-transition-ferromagnetic-metal and dielectric layers in a magnetic tunnel junction (MTJ). However, we need to initiate a new guideline for materials design to improve both the voltage-controlled magnetic anisotropy (VCMA) and perpendicular magnetic anisotropy (PMA). Here we report that atomic-scale doping of iridium in an ultrathin Fe layer is highly effective to improving these properties in Fe/MgO-based MTJs. A large interfacial PMA energy, K i,0 , of up to 3.7 mJ m − 2 was obtained, which was 1.8 times greater than that of the pure Fe/MgO interface. Moreover, iridium doping yielded a huge VCMA coefficient (up to 320 fJ Vm − 1 ) as well as high-speed response. First-principles calculations revealed that Ir atoms dispersed within the Fe layer play a considerable role in enhancing K i,0 and the VCMA coefficient. These results demonstrate the efficacy of heavy-metal doping in ferromagnetic layers as an advanced approach to develop high-density voltage-driven spintronic devices. NPG Asia Materials (2017) 9, e451; doi:10.1038/am.2017.204; published online 5 December 2017 INTRODUCTIONSpintronic devices, such as a magnetoresistive random-access memory device using a MgO-based magnetic tunnel junction (MTJ), 1,2 are expected to reduce the standby power of future computing systems by utilizing the non-volatile feature of magnetism. However, one significant challenge emerges from reducing the energy for information writing: magnetization switching. This issue is caused by electriccurrent-based operations of spintronic devices using electric-currentinduced magnetic fields, spin-transfer torque (STT) and spin-orbit torque based on the spin Hall effect rather than the electric-field-based operations presently used for semiconductor devices. For example, recent developments of STT-magnetoresistive random access memory have achieved~100 fJ per bit writing energies, 3 which corresponds to 10 7 k B T, where k B is the Boltzmann constant and T is the temperature (assumed to be 300 K here). In contrast, the energy required for maintaining magnetic information, that is, thermal stability, is between 60 k B T and 100 k B T. This large energy gap between data writing and retention, on the order of 10 5 , mainly originates

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Section: Resultsmentioning

confidence: 49%

Section: Resultsmentioning

confidence: 87%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Highly efficient voltage control of spin and enhanced interfacial perpendicular magnetic anisotropy in iridium-doped Fe/MgO magnetic tunnel junctions

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Nonvolatile Memristive Materials and Physical Modeling for In‐Memory and In‐Sensor Computing

Go,

Lim,

Lee

et al. 2024

Small Science

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Separate memory and processing units are utilized in conventional von Neumann computational architectures. However, regarding the energy and the time, it is costly to shuffle data between the memory and the processing entity, and for data‐intensive applications associated with artificial intelligence, the demand is ever increasing. A paradigm shift in traditional architectures is required, and in‐memory computing is one of the non‐von‐Neumann computing strategies. By harnessing physical signatures of the memory, computing workloads are administered in the same memory element. For in‐memory computing, a wide range of memristive material (MM) systems have been examined. Moreover, developing computing schemes that perform in the same sensory network and that minimize the data shuffle between the processing unit and the sensing element is a requirement, to process large volumes of data efficiently and decrease the energy consumption. In this review, an overview of the switching character and system signature harnessed in three archetypal MM systems is rendered, along with an integrated application survey for developing in‐sensor and in‐memory computing, viz., brain‐inspired or analogue computing, physical unclonable functions, and random number generators. The recent progress in theoretical studies that reveal the structural origin of the fast‐switching ability of the MM system is further summarized.

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Electric-Field-Controlled MRAM: Physics and Applications

Lourembam

2021

Emerging Non-Volatile Memory Technologies

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

Cited by 154 publications

References 59 publications

Highly efficient voltage control of spin and enhanced interfacial perpendicular magnetic anisotropy in iridium-doped Fe/MgO magnetic tunnel junctions

Highly efficient voltage control of spin and enhanced interfacial perpendicular magnetic anisotropy in iridium-doped Fe/MgO magnetic tunnel junctions

Nonvolatile Memristive Materials and Physical Modeling for In‐Memory and In‐Sensor Computing

Electric-Field-Controlled MRAM: Physics and Applications

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