Field-like spin–orbit torque induced by bulk Rashba channels in GeTe/NiFe bilayers

Jeon, Jun Young; Cho, Seong Won; Lee, OukJae; Hong, Jinki; Kwak, Joon Young; Han, Seungwu; Jung, Soonho; Kim, Yunseok; Ko, Hye-Won; Lee, Jun Young; Lee, Kyung Jin; Koo, Hyun Cheol

doi:10.1038/s41427-021-00344-6

Cited by 8 publications

(3 citation statements)

References 41 publications

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“…We speculate that the TI channel is an extreme case of a Rashba channel; it is therefore reasonable that the field-like torque is much larger than the damping-like torque. Indeed, the previous studies on strong Rashba channels have demonstrated that field-like torques is stronger than damping-like torque in an InAs quantum well and GeTe bulk Rashba channels …”

Section: Resultsmentioning

confidence: 99%

“…Indeed, the previous studies on strong Rashba channels have demonstrated that field-like torques is stronger than dampinglike torque in an InAs quantum well 29 and GeTe bulk Rashba channels. 30 To investigate the gate-controlled spin−orbit field, we modulated the Fermi level of TI using an applied gate voltage to the spin−orbit channel while measuring the secondharmonic signals. Figure 4a shows the gate dependence of the effective spin−orbit field from the harmonic measurement for various gate voltages (Supporting Information S1).…”

Section: ■ Results and Discussionmentioning

confidence: 99%

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Gate Control of Spin–Orbit Torque in a Sputtered Bi₂Se₃/Ni₈₁Fe₁₉ Device

Han

Park

Ahn

et al. 2023

ACS Appl. Electron. Mater.

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Sputtered Bi2Se3 has strong potential for use as a topological insulator in spintronic devices because of its perfect spin polarization and ability to be grown on a large scale. In a Bi2Se3/Ni81Fe19 device, electric field control of spin–orbit torque is clearly observed using second-harmonic measurements. The gate voltage modulates the Fermi level as well as the channel types (i.e., p- or n-type). The strengths of damping-like and field-like torques induced by current are separately extracted for various gate voltages. We find that only damping-like torque is modulated by the gate electric field, showing its maximum value near the Dirac point. In addition, thermal effects mixed with spin–orbit torques are also resolved on the basis of the magnetic field dependence. This work not only evaluates the magnitudes of spin–orbit torques quantitatively but also demonstrates the gate-controlled damping-like torque in a sputtered topological insulator/ferromagnet bilayer.

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Section: Resultsmentioning

confidence: 99%

Section: ■ Results and Discussionmentioning

confidence: 99%

Gate Control of Spin–Orbit Torque in a Sputtered Bi₂Se₃/Ni₈₁Fe₁₉ Device

Han

Park

Ahn

et al. 2023

ACS Appl. Electron. Mater.

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“…Therefore, the deterministic writing is realized by modulating the λ FL /λ DL ratio. Typically, there are some representative methodologies to modulate the ratio of λ FL /λ DL ; for instance, by means of either the bulk Rashba channels enhancement or the interfacial spin accumulation, it is amenable to enhance the FL torque and boost the ratio of λ FL /λ DL up to 4 [54]. By annealing at the proper temperature, the ratio of λ FL /λ DL can be greatly enhanced due to the improvement of interfacial spin transparency [55].…”

Section: Proposed Device Structure and Parameters Optimizationmentioning

confidence: 99%

All-Electrical Control of Compact SOT-MRAM: Toward Highly Efficient and Reliable Non-Volatile In-Memory Computing

et al. 2022

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Two-dimensional van der Waals (2D vdW) ferromagnets possess outstanding scalability, controllable ferromagnetism, and out-of-plane anisotropy, enabling the compact spintronics-based non-volatile in-memory computing (nv-IMC) that promises to tackle the memory wall bottleneck issue. Here, by employing the intriguing room-temperature ferromagnetic characteristics of emerging 2D Fe3GeTe2 with the dissimilar electronic structure of the two spin-conducting channels, we report on a new type of non-volatile spin-orbit torque (SOT) magnetic tunnel junction (MTJ) device based on Fe3GeTe2/MgO/Fe3GeTe2 heterostructure, which demonstrates the uni-polar and high-speed field-free magnetization switching by adjusting the ratio of field-like torque to damping-like torque coefficient in the free layer. Compared to the conventional 2T1M structure, the developed 3-transistor-2-MTJ (3T2M) cell is implemented with the complementary data storage feature and the enhanced sensing margin of 201.4% (from 271.7 mV to 547.2 mV) and 276% (from 188.2 mV to 520 mV) for reading “1” and “0”, respectively. Moreover, superior to the traditional CoFeB-based MTJ memory cell counterpart, the 3T2M crossbar array architecture can be executed for AND/NAND, OR/NOR Boolean logic operation with a fast latency of 24 ps and ultra-low power consumption of 2.47 fJ/bit. Such device to architecture design with elaborated micro-magnetic and circuit-level simulation results shows great potential for realizing high-performance 2D material-based compact SOT magnetic random-access memory, facilitating new applications of highly reliable and energy-efficient nv-IMC.

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Spin Torque Ferromagnetic Resonance Measurements in a Bulk Rashba System

Ahn,

Jeon,

Cho

et al. 2023

Physica Status Solidi (b)

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While many researchers have focused on the interfacial Rashba effect, bulk Rashba materials have received considerable interest due to their potential to enhance spin–orbit torque (SOT). By utilizing GeTe as a bulk Rashba material in the role of a spin–orbit channel, GeTe/Ni81Fe19 and GeTe/Co40Fe40B20 bilayers are fabricated, and SOTs are investigated using the spin torque ferromagnetic (FM) resonance technique. In this method, damping‐like and field‐like SOTs are extracted individually, excluding thermal effects. Upon analyzing the data, a remarkable field‐like SOT efficiency of 0.40 is obtained from the GeTe/Ni81Fe19 system. This high efficiency is attributed to the enhancement of interfacial spin–orbit coupling through the bulk Rashba effect of the GeTe channel. Moreover, noticeable distinctions in SOTs are observed between the Co40Fe40B20 and Ni81Fe19 interfaces, underscoring the importance of selecting the appropriate FM layer for optimizing SOT efficiency. This study highlights the promising potential of bulk Rashba materials like GeTe in advancing SOT‐based devices.

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Field-like spin–orbit torque induced by bulk Rashba channels in GeTe/NiFe bilayers

Cited by 8 publications

References 41 publications

Gate Control of Spin–Orbit Torque in a Sputtered Bi₂Se₃/Ni₈₁Fe₁₉ Device

Gate Control of Spin–Orbit Torque in a Sputtered Bi₂Se₃/Ni₈₁Fe₁₉ Device

All-Electrical Control of Compact SOT-MRAM: Toward Highly Efficient and Reliable Non-Volatile In-Memory Computing

Spin Torque Ferromagnetic Resonance Measurements in a Bulk Rashba System

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Field-like spin–orbit torque induced by bulk Rashba channels in GeTe/NiFe bilayers

Cited by 8 publications

References 41 publications

Gate Control of Spin–Orbit Torque in a Sputtered Bi2Se3/Ni81Fe19 Device

Gate Control of Spin–Orbit Torque in a Sputtered Bi2Se3/Ni81Fe19 Device

All-Electrical Control of Compact SOT-MRAM: Toward Highly Efficient and Reliable Non-Volatile In-Memory Computing

Spin Torque Ferromagnetic Resonance Measurements in a Bulk Rashba System

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Product

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Gate Control of Spin–Orbit Torque in a Sputtered Bi₂Se₃/Ni₈₁Fe₁₉ Device

Gate Control of Spin–Orbit Torque in a Sputtered Bi₂Se₃/Ni₈₁Fe₁₉ Device