Role of transparency of platinum–ferromagnet interfaces in determining the intrinsic magnitude of the spin Hall effect

By Weifeng Zhang, Wei Han, Xin Jiang, See-Hun Yang, Stuart S. P. Parkin. Nature Physics, 2015

528 citations recorded by the source corpus.

The spin Hall effect converts charge current to pure spin currents in orthogonal directions in materials that have significant spin–orbit coupling. The efficiency of the conversion is described by the spin Hall angle (SHA). The SHA can most readily be inferred by using the generated spin currents to excite or rotate the magnetization of ferromagnetic films or nano-elements via spin-transfer torques. Some of the largest spin-torque-derived spin Hall angles (ST-SHA) have been reported in platinum. Here we show, using spin-torque ferromagnetic resonance measurements, that the transparency of the Pt–ferromagnet interface to the spin current plays a central role in determining the magnitude of the ST-SHA. We measure a much larger ST-SHA in Pt/cobalt (∼0.11) compared to Pt/permalloy (∼0.05) bilayers when the interfaces are assumed to be completely transparent. Taking into account the transparency of these interfaces, as derived from spin-mixing conductances, we find that the intrinsic SHA in platinum has a much higher value of 0.19 ± 0.04 as compared to the ST-SHA. The importance of the interface transparency is further exemplified by the insertion of atomically thin magnetic layers at the Pt/permalloy interface that we show strongly modulates the magnitude of the ST-SHA. The spin Hall effect induces spin currents in nonmagnetic layers, which can control the magnetization of neighbouring ferromagnets. The transparency of the interface is shown to strongly influence the efficiency of such manipulation.

Subfields: Atomic and Molecular Physics, and Optics, Electrical and Electronic Engineering

View Paper: https://www.semanticscholar.org/paper/b01baf5ae564efaa69fdd6d5fcb0b67624bcb919

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Atomic and Molecular Physics, and Optics

1. Pietro Gambardella
2. J. Sinova
3. T. Jungwirth
4. A. Manchon
5. G. Sala
6. I. Miron
7. Kevin Garello
8. A. Thiaville

In Electrical and Electronic Engineering

1. J. Sinova
2. A. Manchon
3. T. Jungwirth
4. A. Thiaville
5. Kevin Garello
6. Pietro Gambardella
7. I. Miron
8. J. Železný

Citations in the corpus

• Giant orbital Hall effect and orbital-to-spin conversion in 3d, 5d, and 4f metallic heterostructures (2022, background): “We also notice that interfacial effects (interfacial torques, spin memory loss, and spin transparency) can influence the strength of the torques and hence the spin-orbital conductivity, as shown by the different ξLS measured in Co/Pt and Ni/Pt samples [58].”
• Current-induced spin-orbit torques in ferromagnetic and antiferromagnetic systems (2018, background): “Similar ideas resulted in the proposition of AF skyrmions, either in the bilayer form or in bulk AFs, which display no skyrmion Hall effect and could also reach very high velocity in the latter case (Barker and Tretiakov, 2016; Tomasello et al., 2017; Zhang et al., 2015e).”
• Magnetization oscillations and waves driven by pure spin currents (2016, background): “from 20 nm to 1.5 nm (one unit cell). This calculation also account for an additional correction factor, T indicating how the transmitted spin current JS through the interface contributes effectively [148,149] to the charge current JTJCSSH=Θbeing converted by the spin Hall angle, ΘSH : tanh 2 coth 2”