Giant thermal stability and efficient current-driven motion of chiral magnetic domain walls in ferromagnet-synthetic antiferromagnet lateral junctions

Electrical current driven manipulation of chiral spin textures, such as chiral magnetic domain walls (DWs), is of great interest in both fundamental research and technological applications for spintronic memories, and logic devices^1,2. Of particular interest are synthetic antiferromagnetic racetracks (SAFs) in which antiferromagnetically coupled chiral DWs can be efficiently moved by current³. However, overcoming the trade-off between energy efficiency, namely a low threshold current density to move the DW, and thermal stability still remains a major challenge. Here we show that chiral DWs in a synthetic antiferromagnet-ferromagnet (FM) lateral junction are highly thermally stable whilst the DWs can be efficiently moved across the junction by current⁴. We experimentally demonstrate that thermal fluctuations are equivalent to an effective magnetic field, thereby, surprisingly, increasing the energy barrier and further stabilizing the DW in the junction to even higher temperatures, which is in sharp contrast with conventional FMs or SAFs. Furthermore, we show that chiral DWs can be strongly confined within a FM region sandwiched in between adjacent SAFs and yet can be readily moved into the SAF regions by current. Our novel approaches overcome the aforementioned trade-off thereby allowing for reliable and versatile DW-based memory, and logic, and beyond.

[1] Parkin, S. & Yang, S.-H. Nat. Nanotechnol. 10, 195–198 (2015).

[2] Luo, Z. et al. Nature 579, 214–218 (2020).

[3] Yang, S.-H., Ryu, K.-S. & Parkin, S. Nat. Nanotechnol. 10, 221–226 (2015).

[4] Yoon, J. et al. Nat. Nanotechnol.(2022). https://doi.org/10.1038/s41565-022-01215-z