Orbital torque in light metal/ferromagnet heterostructures

Shilei Ding; William Legrand; Paul Noel; Min-Gu Kang; Pietro Gambardella

doi:10.1117/12.2680723

5 October 2023 Orbital torque in light metal/ferromagnet heterostructures

Shilei Ding, William Legrand, Paul Noel, Min-Gu Kang, Pietro Gambardella

Proceedings Volume PC12656, Spintronics XVI; PC126561Q (2023) https://doi.org/10.1117/12.2680723
Event: SPIE Nanoscience + Engineering, 2023, San Diego, California, United States

Abstract

In bulk transition metals the orbital degree of freedom is normally quenched due to band structure and crystal field effects. However, recent theoretical work indicates that an applied electric field can induce a net flow of orbital angular momentum in transition metals such as Ti, Cr, and Mn. The generation of the orbital current relies on the variable orbital character of the electronic bands that cross the Fermi level and does not require spin-orbit coupling (SOC). This makes it possible to use light metals in spin-orbitronic devices to actively generate orbital and spin currents. In this talk, we will present experimental results evidencing strong orbital torques and orbital Rashba-Edelstein magnetoresistance in light metal/ferromagnet heterostructures. The observation of an orbital torque requires the conversion of the orbital current into a spin current, which occurs due to SOC in the ferromagnetic itself or in nonmagnetic metallic and insulating spacers placed between the light metal and the ferromagnet. Our work shows that the orbital torque can be tuned by choosing orbital-to-spin conversion layers with different SOC, and the magnitude of the orbital torque can be larger than the spin torque. Finally, we will show that orbital currents are also responsible for magnetoresistive effects akin to the spin Hall magnetoresistance.

Conference Presentation

Citation Download Citation

Shilei Ding, William Legrand, Paul Noel, Min-Gu Kang, and Pietro Gambardella "Orbital torque in light metal/ferromagnet heterostructures", Proc. SPIE PC12656, Spintronics XVI, PC126561Q (5 October 2023); https://doi.org/10.1117/12.2680723

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