Current-induced magnetization switching in Pt/Co/Ta with interfacial decoration by insertion of Cr to enhance perpendicular magnetic anisotropy and spin–orbit torques

Cui, Baoshan; Chen, Shiwei; Liu, Dong; Yun, Jijun; Guo, Xiaobin; Wu, Kai; Zhang, Xu; Wang, Yupei; Zuo, Yalu; Gao, Meizhen; Xi, Li

doi:10.7567/apex.11.013001

Cited by 14 publications

(14 citation statements)

References 47 publications

(95 reference statements)

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“…Figure 1d shows that the out-of-plane coercivity (H c ) is slightly enhanced by alloying a small content of Cr and V, which is possibly due to the Cr (or V)/Co interface improving the magnetic anisotropy under optimal conditions. 27,28 As more Cr is incorporated into the Pt−Cr alloy, the H c then starts to decrease because of the reduced interfacial SOC at the Pt/Co interface. 29 3.…”

Section: Introductionmentioning

confidence: 99%

Toward 100% Spin–Orbit Torque Efficiency with High Spin–Orbital Hall Conductivity Pt–Cr Alloys

Chiu

Tsai

et al. 2022

ACS Appl. Electron. Mater.

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5d transition metal Pt is the canonical spin Hall material for efficient generation of spin−orbit torques (SOTs) in Pt/ferromagnetic layer (FM) heterostructures. However, for a long while with tremendous engineering endeavors, the damping-like SOT efficiencies (ξ DL ) of Pt and Pt alloys have still been limited to ξ DL < 0.5. Here we present that with proper alloying elements, particularly 3d transition metals V and Cr, a high spin−orbital Hall conductivity (σ SH ≈ 6.5 × 10 5 (ℏ/2e) Ω −1 m −1 ) can be developed. Especially for the Cr-doped case, an extremely high ξ DL ≈ 0.9 in a Pt 0.69 Cr 0.31 / Co device can be achieved with a moderate Pt 0.69 Cr 0.31 resistivity of ρ xx ≈ 133 μΩ cm. A low critical SOT-driven switching current density of J c ≈ 3.2 × 10 6 A cm −2 is also demonstrated. The damping constant (α) of the Pt 0.69 Cr 0.31 /FM structure is also found to be reduced to 0.052 from the pure Pt/FM case of 0.078. The overall high σ SH , giant ξ DL , moderate ρ xx , and reduced α of such a Pt−Cr/FM heterostructure makes it promising for versatile extremely low power consumption SOT memory applications.

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Section: Introductionmentioning

confidence: 99%

Toward 100% Spin–Orbit Torque Efficiency with High Spin–Orbital Hall Conductivity Pt–Cr Alloys

Chiu

Tsai

et al. 2022

ACS Appl. Electron. Mater.

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“…A typical SOT device consists of heavy metal (HM)/ferromagnet (FM)/oxide layers with a perpendicular magnetic anisotropy (PMA). In this structure, when an in-plane charge current flows in the HM layer, a pure spin-current is generated by the spin-Hall effect (SHE) and/or interfacial Rashba effect and injected into the FM layer to exert SOTs on the magnetization. − Among those kinds of SOTs systems, researchers mainly focused on the current-induced magnetization switching ,− and domain-wall motion. − Ta/CoFeB/MgO trilayer is a typical SOT structure that has been widely studied due to its simplicity and compatibility with a high tunneling magnetoresistance of MgO barrier-based magnetic tunnel junctions, , as well as its significant SOT efficiency. ,− However, the presence of an in-plane external magnetic field is typically required to assist the perpendicular magnetization switching, which is an obstacle for practical applications. Previous works have demonstrated the SOT switching of perpendicularly magnetized Ta/CoFeB/oxide without an external magnetic field by introducing a lateral symmetry-breaking of the structure, − providing a new route to achieve all-electrical deterministic switching.…”

Section: Introductionmentioning

confidence: 99%

Field-Free Spin–Orbit Torque Switching of Perpendicular Magnetization by the Rashba Interface

Cui

Liu

et al. 2019

ACS Appl. Mater. Interfaces

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Current-induced spin–orbit torques (SOTs) enable efficient electrical manipulation of the magnetization in heterostructures with a perpendicular magnetic anisotropy through the Rashba effect or spin-Hall effect. However, in conventional SOT-based heterostructures, an in-plane bias magnetic field along the current direction is required for the deterministic switching. Here, we report that the field-free SOT switching can be achieved by introducing a wedged oxide interface between a heavy metal and a ferromagnet. The results demonstrate that the field-free SOT switching is determined by a current-induced perpendicular effective field (H z eff) originating from the interfacial Rashba effect due to the lateral structural symmetry-breaking introduced by the wedged oxide layer. Furthermore, we show that the sign and magnitude of H z eff exhibit a significant dependence on the interfacial oxygen content, which can be controlled by the inserted oxide thickness. Our findings provide a deeper insight into the field-free SOT switching by the interfacial Rashba effect.

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“…Looking for HMs, such as Pt 4 , 16 – 18 , β -Ta 3 , 18 – 24 , Hf 25 and β -W 26 , 27 with the large θ SH and/or achieving the large effective θ SH based on HM/FM/HM structures in which two HM layers show opposite signs of θ SH 14 , 28 , 29 were carried out more recently. Besides, some reports also reveal that θ SH could be tuned by varying the thickness of HM 15 , 30 , decorating the interface between HM and FM 16 , 31 , 32 , changing the crystallinity of HM 33 and even involving oxygen in HM 34 . Most of these studies can be boiled down to strengthen the driving force for the magnetization reversal and thereby improve the switching efficiency with a lower switching current density.…”

Section: Introductionmentioning

confidence: 99%

Roles of Joule heating and spin-orbit torques in the direct current induced magnetization reversal

Liu

Chen

Zuo

et al. 2018

Sci Rep

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Current-induced magnetization reversal via spin-orbit torques (SOTs) has been intensively studied in heavy-metal/ferromagnetic-metal/oxide heterostructures due to its promising application in low-energy consumption logic and memory devices. Here, we systematically study the function of Joule heating and SOTs in the current-induced magnetization reversal using Pt/Co/SmOx and Pt/Co/AlOx structures with different perpendicular magnetic anisotropies (PMAs). The SOT-induced effective fields, anisotropy field, switching field and switching current density (Jc) are characterized using electric transport measurements based on the anomalous Hall effect and polar magneto-optical Kerr effect (MOKE). The results show that the current-generated Joule heating plays an assisted role in the reversal process by reducing switching field and enhancing SOT efficiency. The out-of-plane component of the damping-like-SOT effective field is responsible for the magnetization reversal. The obtained Jc for Pt/Co/SmOx and Pt/Co/AlOx structures with similar spin Hall angles and different PMAs remains roughly constant, revealing that the coherent switching model cannot fully explain the current-induced magnetization reversal. In contrast, by observing the domain wall nucleation and expansion using MOKE and comparing the damping-like-SOT effective field and switching field, we conclude that the current-induced magnetization reversal is dominated by the depinning model and Jc also immensely relies on the depinning field.

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Current-induced magnetization switching in Pt/Co/Ta with interfacial decoration by insertion of Cr to enhance perpendicular magnetic anisotropy and spin–orbit torques

Abstract: Magnetic trilayers having large perpendicular magnetic anisotropy (PMA) and high spinorbit torques (SOTs) efficiency are the key to fabricate nonvolatile magnetic memory and logic

Cited by 14 publications

References 47 publications

Toward 100% Spin–Orbit Torque Efficiency with High Spin–Orbital Hall Conductivity Pt–Cr Alloys

Toward 100% Spin–Orbit Torque Efficiency with High Spin–Orbital Hall Conductivity Pt–Cr Alloys

Field-Free Spin–Orbit Torque Switching of Perpendicular Magnetization by the Rashba Interface

Roles of Joule heating and spin-orbit torques in the direct current induced magnetization reversal

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