Spin transport across the interface in ferromagnetic/nonmagnetic systems

Swindells, C.; Hindmarch, A. T.; Gallant, Andrew J.; Atkinson, D.

doi:10.1103/physrevb.99.064406

Cited by 31 publications

(26 citation statements)

References 58 publications

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“…These values are in the typical order of magnitude of effective spin mixing conductances obtained for ferromagnetic/Pt systems (for Py/Pt: 21-30 nm −2 [23,29,31,33]; for Co/Pt: 80 nm −2 [26]) and epitaxial Fe/Pt: 26 nm −2 [43]. Especially, for the CoFeB/Pt interface, some reported values are 40 nm −2 [44], 54 nm −2 , and 47 nm −2 for the opposite stacking order, Pt/CoFeB, in [45] and 50.7 nm −2 in [46]). In the case of Ir has been reported for NiFe/Ir interfaces so far 13 nm −2 in [17] and 25.2 nm −2 in [18].…”

Section: Introductionmentioning

confidence: 99%

Determination of spin Hall angle, spin mixing conductance, and spin diffusion length in CoFeB/Ir for spin-orbitronic devices

et al. 2020

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Iridium is a very promising material for spintronic applications due to its interesting magnetic properties such as large RKKY exchange coupling as well as its large spin-orbit coupling value. Ir is for instance used as a spacer layer for perpendicular synthetic antiferromagnetic or ferrimagnet systems. However, only a few studies of the spintronic parameters of this material have been reported. In this paper, we present inverse spin Hall effect -spin pumping ferromagnetic resonance measurements on CoFeB/Ir based bilayers to estimate the values of the effective spin Hall angle, the spin diffusion length within iridium, and the spin mixing conductance in the CoFeB/Ir bilayer. In order to have reliable results, we performed the same experiments on CoFeB/Pt bilayers, which behavior is well known due to numerous reported studies. Our experimental results show that the spin diffusion length within iridium is 1.3 nm for resistivity of 250 nΩ.m, the spin mixing conductance 𝑔 𝑒𝑓𝑓 ↑↓ of the CoFeB/Ir interface is 30 nm -2 , and the spin Hall angle of iridium has the same sign than the one of platinum and is evaluated at 26% of the one of platinum. The value of the spin Hall angle found is 7.7% for Pt and 2% for Ir. These relevant parameters shall be useful to consider Ir in new concepts and devices combining spin-orbit torque and spin-transfer torque.

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Section: Introductionmentioning

confidence: 99%

Determination of spin Hall angle, spin mixing conductance, and spin diffusion length in CoFeB/Ir for spin-orbitronic devices

et al. 2020

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“…The propagation of spin current, both from a magnetic layer into a NM layer, that enhances magnetic damping and, via the spin Hall effect, from a heavy metal into a magnetic layer, that enables spin-orbit torques (SOT), is well established in ferromagnetic systems and has been demonstrated in ferrimagnetic (FiM) systems [4,5]. Such spin transport has also been shown to depend critically upon the details of the interface [6][7][8][9][10][11]. However, debate continues about the role of PIM in such spin transport physics, both with respect to metallic FM/NM systems [12,13] and in insulating ferrimagnets layered with heavy metals (FiM/NM) [14][15][16][17][18][19].…”

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confidence: 99%

Proximity-induced magnetism in Pt layered with rare-earth–transition-metal ferrimagnetic alloys

Swindells

Nicholson

Inyang

et al. 2020

Phys. Rev. Research

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The proximity-induced moment (PIM) in heavy metal layers may play a significant role in heterostructured spintronic systems. In particular, the PIM of a heavy metal adjacent to a magnetic layer has been linked to interfacial spin transport behavior. Element-resolved x-ray magnetic measurements were used to investigate PIM in Pt layered with two different rare-earth (RE):3d transition-metal (TM) ferrimagnetic alloys in which the net moment was dominated by either the RE or the TM at room temperature. We observed significant PIM in Pt confined to a 2-nm interfacial region for Pt/Co 77 Gd 23 and Pt/(Fe 50 Co 50) 77 Gd 23 and, in both cases, the PIM was parallel to the TM sublattice rather than the RE or the net moment. Our results highlight the prominence of the d − d mediated interactions between the Pt and the constituents of the ferrimagnetic RE:TM alloys over the net macroscopic moment.

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“…Precessing magnetization in a ferromagnetic layer can transfer spin angular momentum, in the form of a spin current, into an adjacent NM layer 4 , a process referred to as spin pumping. One of the main manifestations of this spin pumping mechanism is an increase in the precessional damping of a system [5][6][7] and, whilst details remain to be understood, the basis of this process is well described for ferromagnetic/metallic systems 5,8 . However, the propagation of spin current through an insulating barrier has led to conflicting results in the literature.…”

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Spin current propagation through ultra-thin insulating layers in multilayered ferromagnetic systems

Swindells

Hindmarch

Gallant

et al. 2020

Applied Physics Letters

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Spin current pumping from a ferromagnet through an insulating layer into a heavy metal was studied in a CoFeB/SiO2/Pt system in relation to the thickness and interfacial structure of the insulating layer. The propagation of spin current from the ferromagnet into the heavy metal falls rapidly with sub-nanometer thicknesses of SiO2 and is suppressed beyond a nominal thickness of 2 nm. Structural analysis shows that SiO2 only forms a complete barrier layer beyond around 2 nm, indicating that the presence of a discontinuous insulating barrier, and not tunneling or diffusion, explains the main observations of spin-pumping with thin insulating layers.

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Spin transport across the interface in ferromagnetic/nonmagnetic systems

Cited by 31 publications

References 58 publications

Determination of spin Hall angle, spin mixing conductance, and spin diffusion length in CoFeB/Ir for spin-orbitronic devices

Determination of spin Hall angle, spin mixing conductance, and spin diffusion length in CoFeB/Ir for spin-orbitronic devices

Proximity-induced magnetism in Pt layered with rare-earth–transition-metal ferrimagnetic alloys

Spin current propagation through ultra-thin insulating layers in multilayered ferromagnetic systems

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