Thickness Dependence of Interface‐Generated Spin Currents in Ferromagnet/Ti/CoFeB Trilayers

Choi, Gaeun; Ryu, Joonghyun; Lee, Sung-Jun; Kang, Jaimin; Noh, Namgyu; Yuk, Jong Min; Park, Byong‐Guk

doi:10.1002/admi.202201317

Cited by 5 publications

(3 citation statements)

References 79 publications

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“…Due to the spin-orbit filtering, the incoming unpolarized carriers can become spin-polarized by spindependent reflection and transmission at the interface. Moreover, it was recently reported that the sign of the spin current from the spin-orbit filtering effect is related to the magnitude of the charge current in the two materials that constitute the interface [37]. The resistivities of Ru (10 nm) and Cu (10 nm) in our study are about 9.4 and 3.8 μΩ cm, respectively.…”

Section: St-fmr Measurementsupporting

confidence: 46%

“…Experimentally, Baek et al demonstrated the interface-generated spin currents in the CoFeB/Ti and NiFe/Ti bilayer structures [36]. It was also shown that the sign and magnitude of the spin currents could be modulated by adjusting the electrical conductivity of the two materials forming the interface [37]. These results suggest the great potential of well-controlled nanostructures and interfaces for improving spin-charge conversion efficiency.…”

Section: Introductionmentioning

confidence: 99%

“…Nevertheless, it has been found that the atomicscale oxidation of Cu can generate a large spin current with comparable ξ SH to Pt, which can be explained by the spin vorticity coupling of the electron mobility gradient [28], or the enhanced interfacial SOIs, such as Rahsba effect [27,32,33]. Moreover, interfacial and layered structure engineering in light-metal-based heterostructures also generates significant spin currents [34][35][36][37]. Jamali et al reported the enhanced efficiencies of SOTs in multilayer-stacked Co/Pd, owing to a probable bulk contribution of the multilayers [34].…”

Section: Introductionmentioning

confidence: 99%

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Charge-to-spin conversion in fully epitaxial Ru/Cu hybrid nanolayers with interface control

Song

Scheike

et al. 2023

Nanotechnology

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The demonstration of the spin-charge conversion, especially with enhanced spin Hall conductivity, is crucial for the development of energy-efficient spintronic devices such as spin-orbital torque (SOT) based magnetoresistive random access memories. In this work, fully epitaxial Ru/Cu heterostructures were fabricated with interface engineering and nanolayer insertions consisting of Cu (1nm)/Ru (1nm) structures with different numbers of periods. The atomically controlled interface was confirmed by the high-resolution high-angle annular dark-field scanning transmission electron microscopy, and the epitaxial relationship persists even in the hybrid nanolayer insertion structures. The spin current generation was detected by the measurement of unidirectional spin Hall magnetoresistance, and the effective damping-like spin Hall efficiency (ξ_DL) was further quantitatively evaluated by the spin-torque ferromagnetic resonance with thickness dependence of the ferromagnetic layer. It is found that the sharp interface Ru/Cu film has a sizeable ξ_DL of −2.2% and the insertion of Cu/Ru nanolayers at the interface can increase the ξ_DL value to −3.7%. The former could be attributed to the interface spin-orbit filtering effect and the latter may be further understood by the intrinsic contribution from the local electronic structure tuning due to the lattice distortion near the interface. A large effective spin Hall conductivity is achieved to be (3~5)×10^5 ℏ/2eΩ^(−1)m^(−1) in the epitaxial Ru/Cu hybrid nanolayers, which is in the same range as that of platinum. This work indicates that the interfacial control with hybrid nanolayer structures can extend the SOT-based materials to highly conductive metals, even with weak spin-orbit interactions, toward high stability, low cost, and low energy consumption for spintronic applications.

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Section: St-fmr Measurementsupporting

confidence: 46%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Charge-to-spin conversion in fully epitaxial Ru/Cu hybrid nanolayers with interface control

Song

Scheike

et al. 2023

Nanotechnology

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Structural, magnetic, and thermomagnetic properties of Co2FeAl/(W,Ti) thin films: Role of non-ferromagnetic metal thickness

Siqueira,

Baptista,

Lopes

et al. 2023

Sensors and Actuators A: Physical

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Spin current and spin-orbit torque induced by ferromagnets

Kim,

Park,

Lee

2024

npj Spintronics

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Spin torque is typically classified based on how the spin current is generated and injected into a magnet for manipulation. Spin-orbit torque arises from the spin-orbit interaction in a nearby normal metal, while spin-transfer torque results from exchange interactions in another ferromagnet. Recent studies have suggested that a ferromagnet itself can also generate a spin current through spin-orbit coupling, leading to the emergence of ferromagnet-induced spin-orbit torque as another class of spin torque. This novel torque mechanism not only inherits the advantages of spin-orbit torque architectures, such as separate reading and writing paths in memory applications but also offers the flexibility to control the generated spin direction by manipulating the orientation of the ferromagnet responsible for generating the spin current. In this article, we review the phenomena related to spin currents generated by ferromagnets, explore their physical descriptions in heterostructures, and discuss several spin torque architectures based on this effect. Ferromagnet-induced spin-orbit torque not only introduces new physical consequences by combining spin-orbit and exchange interactions but also offers a promising building block in spintronics with significant potential for diverse applications.

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Thickness Dependence of Interface‐Generated Spin Currents in Ferromagnet/Ti/CoFeB Trilayers

Cited by 5 publications

References 79 publications

Charge-to-spin conversion in fully epitaxial Ru/Cu hybrid nanolayers with interface control

Charge-to-spin conversion in fully epitaxial Ru/Cu hybrid nanolayers with interface control

Structural, magnetic, and thermomagnetic properties of Co2FeAl/(W,Ti) thin films: Role of non-ferromagnetic metal thickness

Spin current and spin-orbit torque induced by ferromagnets

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