Unidirectional Anisotropy in Permalloy Films at 4.2°K

Bailey, Sheila B.; Peterlin, Tatjana M.; Richard, Roy T.; Mitchell, E. N.

doi:10.1063/1.1658320

Cited by 12 publications

(6 citation statements)

References 7 publications

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“…The most likely cause for the reduced electrical spin injection is the formation of oxidized permalloy at the FM/NM junction that was not fully removed by the RF cleaning step before Al deposition. Native permalloy oxides can be complicated chemically and magnetically [62], though typically are not seen to develop long-range magnetic order above ∼ 30 K [63][64][65]. However, the permalloy oxide is a likely source of intermediate energy states in the barrier with random local magnetic environments that could easily contribute to loss of spin fidelity as initially spin-polarized electrons transport from Py to Al.…”

Section: Discussionmentioning

confidence: 99%

Thermal spin injection and interface insensitivity in permalloy/aluminum metallic nonlocal spin valves

2016

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We present measurements of thermal and electrical spin injection in nanoscale metallic non-local spin valve (NLSV) structures. Informed by measurements of the Seebeck coefficient and thermal conductivity of representative films made using a micromachined Si-N thermal isolation platform, we use simple analytical and finite element thermal models to determine limits on the thermal gradient driving thermal spin injection and calculate the spin dependent Seebeck coefficient to be −0.5 µV/K < S s < −1.6 µV/K. This is comparable in terms of the fraction of the absolute Seebeck coefficient to previous results, despite dramatically smaller electrical spin injection signals.Since the small electrical spin signals are likely caused by interfacial effects, we conclude that thermal spin injection is less sensitive to the FM/NM interface, and possibly benefits from a layer of oxidized ferromagnet, which further stimulates interest in thermal spin injection for applications in sensors and pure spin current sources.1 arXiv:1602.03859v2 [cond-mat.mes-hall]

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Section: Discussionmentioning

confidence: 99%

Thermal spin injection and interface insensitivity in permalloy/aluminum metallic nonlocal spin valves

2016

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“…4 were taken at room temperature, much higher than the temperature where magnetic order is normally believed to occur in oxidized permalloy of this thickness. [38][39][40] We address these issues in much more detail below (Sec. IV A).…”

Section: 0±02 G/cmmentioning

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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“…24. The asymmetric switching is due to the unidirectional anisotropy in the Py wires, possibly induced by the natural surface oxidation 25 after the lift-off process. The spin signal is clearly reduced compared with the spin signal of 1.2 m⍀ for the reference spin valve without the inserted Nb wire.…”

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confidence: 99%

Nonlocal injection of spin current into a superconducting Nb wire

Ohnishi

Kimura

Otani

2010

Applied Physics Letters

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Pure spin current injection into a superconductive Nb was demonstrated experimentally by employing a nonlocal spin absorption technique in a multiterminal lateral structure. From the reduction in spin signals, we found the absorption efficiency remained almost unchanged even after superconducting transition. The Nb/Cu interface properties were also complementarily examined by using a Nb/Cu/Nb junction incorporated in the same device, revealing superconductivity below the transition temperature. These experimental results support that the pure spin current can be absorbed into a superconductive Nb wire with almost the same efficiency as in a normal state.

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Unidirectional Anisotropy in Permalloy Films at 4.2°K

Cited by 12 publications

References 7 publications

Thermal spin injection and interface insensitivity in permalloy/aluminum metallic nonlocal spin valves

Thermal spin injection and interface insensitivity in permalloy/aluminum metallic nonlocal spin valves

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

Nonlocal injection of spin current into a superconducting Nb wire

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