Effect of Ta insertion between Pt and CoFeB on interfacial magnetic anisotropy in Pt/CoFeB/MgO multilayer thin-film stack

Akyol, Mustafa; Kıvrak, Burak; Tümen, Kutluhan Utku; Ekicibil, Ahmet

doi:10.1007/s10854-020-04831-4

Cited by 5 publications

(1 citation statement)

References 42 publications

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“…Heavy metals such as Pt, Ta, and W are commonly used as spin sources in ferromagnet-heavy-metal (FM/HM) heterostructures, where spin currents are generated via the spin Hall effect due to strong spin-orbit coupling [4][5][6][7]. However, further development of HM-based SOT devices has been limited by the spin Hall angle (<1) [7][8][9][10][11]. Owing to recent advancements, topological insulators (TIs) have gained much attention due to their unique spin-momentum locking and topologically protected surface states [12][13][14][15][16][17] [see Fig.…”

Section: Introductionmentioning

confidence: 99%

Crystallinity Control of the Topological-Insulator Surface Bi85Sb15(012) via Interfacial Engineering for Enhanced Spin-Orbit Torque

et al. 2023

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Topological insulators demonstrate high charge-spin conversion efficiency due to their spin-momentum locking at the Dirac surface states. However, the surface states are sensitive to disruption caused by exchange coupling when interfaced with a ferromagnet. Here, we demonstrate the use of various nonmagnetic insertion layer materials, Ti, Cu, and Pt, at the Co/Bi-Sb(012) interface to preserve the topological surface state and promote spin-orbit-torque efficiency through the crystallinity control of Bi-Sb(012). For 20-nm-thick Bi-Sb, a spin Hall angle of up to 8.93 is observed with the use of a Pt insertion layer, while it is otherwise negligible for Co/Bi-Sb(012) interfaces. We further explore the enhancement of Bi-Sb(012) crystallinity with increasing Bi-Sb thickness, revealing a rapidly increasing spin-orbit-torque efficiency that gradually saturates above 30 nm. A clear correlation between spin-orbit-torque efficiency and Bi-Sb(012) crystalline size is identified using x-ray diffractometry, establishing the origin of the high spin-orbit efficiency to be the Bi-Sb(012) crystalline orientation. Our work demonstrates the spin-orbittorque origin in Bi-Sb experimentally and paves the way for the adaptation of topological insulators as a class of low-energy spin source material for spintronics applications.

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Section: Introductionmentioning

confidence: 99%

Crystallinity Control of the Topological-Insulator Surface Bi85Sb15(012) via Interfacial Engineering for Enhanced Spin-Orbit Torque

et al. 2023

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Enhanced Voltage‐Controlled Magnetic Anisotropy and Field‐Free Magnetization Switching Achieved with High Work Function and Opposite Spin Hall Angles in W/Pt/W SOT Tri‐Layers

Chen,

Jia,

Yang

et al. 2024

Adv Funct Materials

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Voltage‐Gated Spin‐Orbit‐Torque (VGSOT) Magnetic Random‐Access Memory (MRAM) is a promising candidate for reducing writing energy and improving writing speed in emerging memory and in‐memory computing applications. However, conventional Voltage Controlled Magnetic Anisotropy (VCMA) approaches are often inefficient due to the low VCMA coefficient at the CoFeB/MgO interface. Additionally, traditional heavy metal/perpendicular magnetic anisotropy (PMA) ferromagnet bilayers require an external magnetic field to overcome symmetry constraints and achieve deterministic SOT switching. Here, a novel and industry‐compatible SOT underlayer for next‐generation VGSOT MRAM by employing a composite heavy metal tri‐layer with a high work function is presented. This approach achieves a VCMA coefficient exceeding 100 fJ V−1m−1 through electron depletion effects, which is ten times larger than that observed with a pure W underlayer. Furthermore, it is demonstrated that this composite heavy metal SOT underlayer facilitates the integration of VCMA with opposite spin Hall angles, enabling field‐free SOT switching in industry‐compatible PMA CoFeB/MgO systems.

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Stack structure and CoFeB composition dependence of perpendicular magnetic anisotropy employing Pt heavy metal layer

Liu

Wang

et al. 2022

Journal of Alloys and Compounds

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Effect of Ta insertion between Pt and CoFeB on interfacial magnetic anisotropy in Pt/CoFeB/MgO multilayer thin-film stack

Cited by 5 publications

References 42 publications

Crystallinity Control of the Topological-Insulator Surface Bi85Sb15(012) via Interfacial Engineering for Enhanced Spin-Orbit Torque

Crystallinity Control of the Topological-Insulator Surface Bi85Sb15(012) via Interfacial Engineering for Enhanced Spin-Orbit Torque

Enhanced Voltage‐Controlled Magnetic Anisotropy and Field‐Free Magnetization Switching Achieved with High Work Function and Opposite Spin Hall Angles in W/Pt/W SOT Tri‐Layers

Stack structure and CoFeB composition dependence of perpendicular magnetic anisotropy employing Pt heavy metal layer

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