Fieldlike and antidamping spin-orbit torques in as-grown and annealed Ta/CoFeB/MgO layers

By C. Avci, Kevin Garello, C. Nistor, S. Godey, B. Ballesteros, A. Mugarza, A. Barla, M. Valvidares, E. Pellegrin, Abhijit Ghosh and 5 more. 2014

190 citations recorded by the source corpus.

We present a comprehensive study of the current-induced spin-orbit torques in perpendicularly magnetized Ta/CoFeB/MgO layers. The samples were annealed in steps up to 300 \ifmmode^\circ\else\textdegree\fi{}C and characterized using x-ray-absorption spectroscopy, transmission electron microscopy, resistivity, and Hall effect measurements. By performing adiabatic harmonic Hall voltage measurements, we show that the transverse (fieldlike) and longitudinal (antidampinglike) spin-orbit torques are composed of constant and magnetization-dependent contributions, both of which vary strongly with annealing. Such variations correlate with changes of the saturation magnetization and magnetic anisotropy and are assigned to chemical and structural modifications of the layers. The relative variation of the constant and anisotropic torque terms as a function of annealing temperature is opposite for the fieldlike and antidamping torques. Measurements of the switching probability using sub-\ensuremath{\mu}s current pulses show that the critical current increases with the magnetic anisotropy of the layers, whereas the switching efficiency, measured as the ratio of magnetic anisotropy energy and pulse energy, decreases. The optimal annealing temperature to achieve maximum magnetic anisotropy, saturation magnetization, and switching efficiency is determined to be between 240 and 270 \ifmmode^\circ\else\textdegree\fi{}C.

Subfields: Atomic and Molecular Physics, and Optics, Condensed Matter Physics, Materials Chemistry

View Paper: https://www.semanticscholar.org/paper/ec5f2d3f3214cf9017a304fe0f44f8b7fc16437c

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In Atomic and Molecular Physics, and Optics

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

In Condensed Matter Physics

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

In Materials Chemistry

1. J. Sinova
2. Pietro Gambardella
3. A. Manchon
4. T. Jungwirth
5. T. Dietl

Citations in the corpus

• Current-induced spin-orbit torques in ferromagnetic and antiferromagnetic systems (2018, methodology): “…shown that the DL and FL SOTs change dramatically upon annealing and consequent intermixing of Pt/Co/AlOx (Garello et al., 2013) and Ta/CoFeB/MgO (Avci et al., 2014b), as well as upon the insertion of different spacer layers between the FM and the NM that is considered to be the main source of…”