Yang, X., Fang, S., Yang, Z., Ho, P., Lu, J., & Ang, Y. S. (2026). Altermagnetic Flatband‐Driven Fermi Surface Geometry for Giant Tunneling Magnetoresistance. Advanced Functional Materials. Portico. https://doi.org/10.1002/adfm.202531921
Abstract:
ABSTRACT
Altermagnetism, characterized by zero net magnetization and symmetry‐protected spin–split band structures, has recently emerged as a promising platform for spintronics. In altermagnetic tunnel junctions (AMTJs), the suppression of tunneling in the antiparallel configuration relies on the mismatch between spin‐polarized conduction channels in momentum space. However, ideal nonoverlapping spin‐polarized Fermi surfaces are rarely found in bulk altermagnets. Motivated by the critical influence of Fermi surface geometry on tunneling magnetoresistance (TMR), we investigate three experimentally synthesized altermagnets – bulk , , and – to elucidate how flatband‐driven Fermi surfaces minimize spin‐channel overlap and boost AMTJ performance. Notably, and host flat altermagnetic Fermi sheets, which confine spin degeneracy to minimal arc‐like or nodal‐like regions. Such Fermi surface geometry drastically reduces spin overlap, resulting in an unprecedented intrinsic TMR well over in the ‐based AMTJ. Incorporating an insulating barrier further enhances the TMR to , surpassing most conventional MTJs. These results not only establish as a compelling candidate AMTJ material, but also highlight the critical role of flatband Fermi surface geometry in achieving high‐performance altermagnetic‐spintronic device technology.
License type:
Publisher Copyright
Funding Info:
This research / project is supported by the Ministry of Education - Academic Research Fund Tier 2
Grant Reference no. : MOE-T2EP50224-0021
Description:
This is the peer reviewed version of the following article: Yang, X., Fang, S., Yang, Z., Ho, P., Lu, J., & Ang, Y. S. (2026). Altermagnetic Flatband‐Driven Fermi Surface Geometry for Giant Tunneling Magnetoresistance. Advanced Functional Materials. Portico. https://doi.org/10.1002/adfm.202531921, which has been published in final form at https://doi.org/10.1002/adfm.202531921. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. This article may not be enhanced, enriched or otherwise transformed into a derivative work, without express permission from Wiley or by statutory rights under applicable legislation. Copyright notices must not be removed, obscured or modified. The article must be linked to Wiley’s version of record on Wiley Online Library and any embedding, framing or otherwise making available the article or pages thereof by third parties from platforms, services and websites other than Wiley Online Library must be prohibited.