Observation of anti-damping spin-orbit torques generated by in-plane and out-of-plane spin polarizations in MnPd3

DC, Mahendra; Shao, Ding-Fu; Hou, Vincent D. -H.; Quarterman, P.; Habiboglu, Ali; Brooks, Venuti,; Miura, Masashi; Kirby, Brian J.; Vailionis, Artūras; Bi, Chong; Li, Xiang; Xue, Fengxia; Huang, Yen‐Lin; Deng, Yong; Lin, Shy-Jay; Tsai, W.; Eley, Serena; Wang, Weigang; Borchers, Julie; Tsymbal, Evgeny Y.; Wang, Shan X.

doi:10.48550/arxiv.2012.09315

Cited by 4 publications

(6 citation statements)

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“…. Within the approximation of an in-plane magnetized macrospin, the angle dependence of the second HHVR (V2ω) under a sinusoidal electric field E = 25.4 kV/m and an in-plane magnetic bias field (H) follows 19,20,34,35 :…”

Section: (F))mentioning

confidence: 99%

“…Experimentally, it is widely assumed that the presence of σz could be concluded from a small but sizable sin2φ dependent contribution in spin torque ferromagnetic resonance (ST-FMR) 2,7,8,[16][17][18] or a φ independent second harmonic Hall voltage response (HHVR) 5,19,20 of an in-plane magnetization (φ is the angle of external magnetic field with respect to the current). Presence of σz is also claimed from the occurrence of external-field-free current switching of a uniform perpendicular magnetization 4,[9][10][11][12][13][14][15] because the polarization and fieldlike spin-orbit torque (SOT) field of σz, if any, are along the film normal.…”

Section: Introductionmentioning

confidence: 99%

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Current-induced perpendicular effective magnetic field in magnetic heterostructures

Liu

Zhu

2022

Applied Physics Reviews

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The generation of perpendicular effective magnetic field or perpendicular spins ( σz) is central for the development of energy-efficient, scalable, and external-magnetic-field-free spintronic memory and computing technologies. Here, we report the first identification and the profound impacts of a significant effective perpendicular magnetic field that can arise from asymmetric current spreading within magnetic microstrips and Hall bars. This effective perpendicular magnetic field can exhibit all the three characteristics that have been widely assumed in the literature to “signify” the presence of a flow of σz, i.e., external-magnetic-field-free current switching of uniform perpendicular magnetization, a sin 2 φ-dependent contribution in spin-torque ferromagnetic resonance signal of in-plane magnetization ( φ is the angle of the external magnetic field with respect to the current), and a φ-independent but field-dependent contribution in the second harmonic Hall voltage of in-plane magnetization. This finding suggests that it is critical to include current spreading effects in the analyses of various spin polarizations and spin–orbit torques in the magnetic heterostructure. Technologically, our results provide a perpendicular effective magnetic field induced by asymmetric current spreading as a novel, universally accessible mechanism for efficient, scalable, and external-magnetic-field-free magnetization switching in memory and computing technologies.

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Section: (F))mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Current-induced perpendicular effective magnetic field in magnetic heterostructures

Liu

Zhu

2022

Applied Physics Reviews

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“…For producing perpendicularly polarized spin-current through materials innovation, one needs to include the discussion of in-plane symmetry control for such SOT materials at an early stage. For example, non-magnetic materials with a lack of crystal inversion symmetry can produce perpendicularly polarized spins [62,104]. However, methods have to be developed to control their crystal orientation on an amorphous or polycrystalline base-layer -the type of substrate surfaces typically encountered in back-end CMOS integration environment.…”

Section: Materials Compatibilitymentioning

confidence: 99%

A Perspective on Electrical Generation of Spin Current for Magnetic Random Access Memories

Safranski,

Sun,

Kent

2022

Preprint

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Spin currents are used to write information in magnetic random access memory (MRAM) devices by switching the magnetization direction of one of the ferromagnetic electrodes of a magnetic tunnel junction (MTJ) nanopillar. Different physical mechanisms of conversion of charge current to spin current can be used in 2-terminal and 3-terminal device geometries. In 2-terminal devices, charge-to-spin conversion occurs by spin filtering in the MTJ's ferromagnetic electrodes and present day MRAM devices operate near the theoretically expected maximum charge-to-spin conversion efficiency. In 3-terminal devices, spin-orbit interactions in a channel material can also be used to generate large spin currents. In this perspective article, we discuss charge-to-spin conversion processes that can satisfy the requirements of MRAM technology. We emphasize the need to develop channel materials with larger charge-to-spin conversion efficiency-that can equal or exceed that produced by spin filtering-and spin currents with a spin polarization component perpendicular to the channel interface. This would enable high-performance devices based on sub-20 nm diameter perpendicularly magnetized MTJ nanopillars without need of a symmetry breaking field. We also discuss MRAM characteristics essential for CMOS integration. Finally, we identify critical research needs for charge-to-spin conversion measurements and metrics that can be used to optimize device channel materials and interface properties prior to full MTJ nanopillar device fabrication and characterization.

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“…(c) Experimentally obtained damping-like spin-torque efficiency data fitted using drift-diffusion based model for the case of AuPt, 17 β-W, 18,19 and MnPd3. 20 The symbols represent the experimental data while the solid curves refer to the model. Table 1.…”

Section: Introductionmentioning

confidence: 99%

Modeling of spin-orbit torque (SOT) channel and high-density SOT magnetic random-access memory

Kumar,

Naeemi

2023

Spintronics XVI

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Spin-orbit torque (SOT) devices are being pursued for various memory and in-memory compute applications. At nanoscale dimensions, electric current flowing through the SOT channel can be non-uniform due to incomplete current redistribution. Such effects were ignored in the prior modeling works. We present a comprehensive modeling framework for SOT devices that capture the effects of incomplete current redistribution along with interface spin-mixing, and non-uniform resistivity. Our transfer matrix-based formalism along with finite element simulations can account for any local variation in resistivity and spin diffusion length along with accounting for various spin-scattering mechanisms. In addition, we quantify the optimal SOT layer thickness to minimize the write energy in terms of its resistivity and spin diffusion length. To improve the bit density of SOT magnetic random-access memory (MRAM), we explore area saving schemes based on sharing SOT channel among multiple magnetic tunnel junctions (MTJs) with the help of voltage-controlled magnetic anisotropy (VCMA) effect and spin-transfer torque (STT). Using micromagnetic simulations, we study various tradeoffs among write time, current, error rate, and the number of MTJs. Our results show that the number of MTJs on the shared SOT channel is limited by the voltage drop over the SOT channel and write error rate, and having more than 4 MTJs on a SOT channel poses major challenges in terms of reliability.

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Observation of anti-damping spin-orbit torques generated by in-plane and out-of-plane spin polarizations in MnPd3

Cited by 4 publications

References 0 publications

Current-induced perpendicular effective magnetic field in magnetic heterostructures

Current-induced perpendicular effective magnetic field in magnetic heterostructures

A Perspective on Electrical Generation of Spin Current for Magnetic Random Access Memories

Modeling of spin-orbit torque (SOT) channel and high-density SOT magnetic random-access memory

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