Shape anisotropy revisited in single-digit nanometer magnetic tunnel junctions

• Published in: Nature communications Vol. 9; no. 1; pp. 663 - 6
• Main Authors: Watanabe, K., Jinnai, B., Fukami, S., Sato, H., Ohno, H.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 14.02.2018; Nature Publishing Group; Nature Portfolio
• Subjects: 147/137; 147/143; 639/166/987; 639/766/119/1001; 639/925/927/1062; Anisotropy; Computer memory; Humanities and Social Sciences; Magnetic anisotropy; Magnetic switching; Magnetization; Magnetoresistivity; multidisciplinary; Random access; Random access memory; Science; Science (multidisciplinary); Spintronics; Thermal stability; Tunnel junctions
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-018-03003-7

Nanoscale magnetic tunnel junctions play a pivotal role in magnetoresistive random access memories. Successful implementation depends on a simultaneous achievement of low switching current for the magnetization switching by spin transfer torque and high thermal stability, along with a continuous reduction of junction size. Perpendicular easy-axis CoFeB/MgO stacks possessing interfacial anisotropy have paved the way down to 20-nm scale, below which a new approach needs to be explored. Here we show magnetic tunnel junctions that satisfy the requirements at ultrafine scale by revisiting shape anisotropy, which is a classical part of magnetic anisotropy but has not been fully utilized in the current perpendicular systems. Magnetization switching solely driven by current is achieved for junctions smaller than 10 nm where sufficient thermal stability is provided by shape anisotropy without adopting new material systems. This work is expected to push forward the development of magnetic tunnel junctions toward single-digit nm-scale nano-magnetics/spintronics. The thermal stability impedes the application of nanoscale magnetic tunnel junctions in electronic and spintronics devices. Here the authors achieved current-induced magnetization switching in magnetic tunnel junctions smaller than 10 nm with sufficient thermal stability due to the shape anisotropy without adding new material systems.