Abnormal spin-pumping effect at Pt/NiFe interface by an oxidation of ferromagnet

Kim, Sang Il; Seo, Min Hong; Seo, Jung‐Hye; Woo, Han Young; Lee, Jun Young; Choi, Yeon Suk; Park, Seung-young

doi:10.1016/j.cap.2014.10.004

Cited by 5 publications

(3 citation statements)

References 22 publications

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“…A 10 nm permalloy (Py = Ni 80 Fe 20 ) film is used as FM layer and source of spins. The Py film is passivated with a 6 nm AlO x film which protects the FM from oxidation in order to avoid the detrimental effects of oxidised Py on the spin pumping efficiency 55 . The Py/n-GaN:Si bilayer is driven to resonance conditions at room temperature under an X-band microwave excitation of (9.44 ± 0.01) GHz with an external magnetic field in a Bruker Elexsys E580 electron paramagnetic resonance spectrometer.…”

Section: Methodsmentioning

confidence: 99%

Rashba semiconductor as spin Hall material: Experimental demonstration of spin pumping in wurtziten-GaN:Si

et al. 2016

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Pure spin currents in semiconductors are essential for implementation in the next generation of spintronic elements. Heterostructures of III-nitride semiconductors are currently employed as central building-blocks for lighting and high-power devices. Moreover, the long relaxation times and the spin-orbit coupling (SOC) in these materials indicate them as privileged hosts for spin currents and related phenomena. Spin pumping is an efficient mechanism for the inception of spin current and its conversion into charge current in non-magnetic metals and semiconductors with Rashba SOC via spin Hall effects. We report on the generation in n-GaN:Si -at room temperature and through spin pumping -of pure spin current, fundamental for the understanding of the spin dynamics in these non-centrosymmetric Rashba systems. We find for n-GaN:Si a spin Hall angle θSH=3.03 × 10 −3 , exceeding by one order of magnitude those reported for other semiconductors, pointing at III-nitrides as particularly efficient spin current generators.

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Section: Methodsmentioning

confidence: 99%

Rashba semiconductor as spin Hall material: Experimental demonstration of spin pumping in wurtziten-GaN:Si

et al. 2016

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“…are somewhat rare and have tested very different regimes that either involve long-term oxidation of the entire FM film 18 or demonstrated only a change in damping that could have other origins.…”

Section: B Physical Origin Of Enhanced V Ish With Native Oxidesmentioning

confidence: 99%

Efficient spin transport through native oxides of nickel and permalloy with platinum and gold overlayers

et al. 2016

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We present measurements of spin pumping detected by the inverse spin Hall effect voltage and ferromagnetic resonance spectroscopy in a series of metallic ferromagnet/normal metal thin film stacks. We compare heterostructures grown in situ to those where either a magnetic or nonmagnetic oxide is introduced between the two metals. The heterostructures, either nickel with a platinum overlayer (Ni/Pt) or the nickel-iron alloy permalloy (Py) with a gold overlayer (Py/Au), were also characterized in detail using grazing-incidence X-ray reflectivity, Auger electron spectroscopy, and both SQUID and alternating-gradient magnetometry. We verify the presence of oxide layers, characterize layer thickness, composition, and roughness, and probe saturation magnetization, coercivity, and anisotropy. The results show that while the presence of a non-magnetic oxide at the interface suppresses spin transport from the ferromagnet to the non-magnetic metal, a thin magnetic oxide (here the native oxide formed on both Py and Ni) somewhat enhances the product of the spin mixing conductance and the spin Hall angle. We also observe clear evidence of an out-of-plane component of magnetic anisotropy in Ni/Pt samples that is enhanced in the presence of the native oxide, resulting in perpendicular exchange bias. Finally, the dc inverse spinHall voltages generated at ferromagnetic resonance in our Py/Au samples are large, and suggest values for the spin Hall angle in gold of 0.04 < α SH < 0.22, in line with the highest values reported for Au. This is interpreted as resulting from Fe impurities. We present indirect evidence that the Au films described here indeed have significant impurity levels.2

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“…This data provides strong evidence about the nature of the interface that is exposed to oxygen. For the case of a CoFe/oxide interface, spinpumping at the CoFe/oxide interface is expected to be strongly suppressed [36][37][38][39].…”

Section: Resultsmentioning

confidence: 99%

Variation of sign and magnitude of the Dzyaloshinskii-Moriya interaction of a ferromagnet with an oxide interface

2020

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We demonstrate that both the magnitude and sign of the Dzyaloshinskii-Moriya interaction can be tuned by modifying the type and thickness of an oxide layer adjacent to a ferromagnet. We focus on Ti/Cu/Co90Fe10/Ta(dTa)/Oxide/Ta structures, where the Ta interlayer thickness dTa ranged from 0 nm to 3 nm, followed by an exposure to oxygen and "Oxide" can mean CoFeOx and/or TaOx. We used Brillouin light scattering spectroscopy to directly determine the volume-averaged Dzyaloshinkii-Moriya interaction from the nonreciprocity of the spin-wave frequency. The magnitude of the interfacial Dzyaloshinkskii-Moriya interaction, DDMI, ranges from -0.17 to + 0.09 (± 0.02) mJ/m 2 , clearly showing a change in both sign and magnitude, with an increase of Ta interlayer thickness. The modification of the oxide interface allows us to systematically change the hybridization of the 3d-CoFe orbitals from 3d-5d to 3d-2p and analyze the influence on the Dzyaloshinskii-Moriya interaction. Importantly, we can vary the Dzyaloshinskii-Moriya interaction while maintaining a relatively small value of the damping parameter.

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Abnormal spin-pumping effect at Pt/NiFe interface by an oxidation of ferromagnet

Cited by 5 publications

References 22 publications

Rashba semiconductor as spin Hall material: Experimental demonstration of spin pumping in wurtziten-GaN:Si

Rashba semiconductor as spin Hall material: Experimental demonstration of spin pumping in wurtziten-GaN:Si

Efficient spin transport through native oxides of nickel and permalloy with platinum and gold overlayers

Variation of sign and magnitude of the Dzyaloshinskii-Moriya interaction of a ferromagnet with an oxide interface

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