Field-free Magnetization Switching by Utilizing the Spin Hall Effect and Interlayer Exchange Coupling of Iridium

• Published in: Scientific reports Vol. 9; no. 1; p. 325
• Main Authors: Liu, Yang, Zhou, Bing, Zhu, Jian-Gang (Jimmy)
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 23.01.2019; Nature Publishing Group
• Subjects: 142/126; 639/301/119/1001; 639/301/119/997; Electromagnetism; Humanities and Social Sciences; Iridium; Magnetism; multidisciplinary; Random access memory; Science; Science & Technology - Other Topics; Science (multidisciplinary)
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-018-37586-4

Magnetization switching by spin-orbit torque (SOT) via spin Hall effect represents as a competitive alternative to that by spin-transfer torque (STT) used for magnetoresistive random access memory (MRAM), as it doesn’t require high-density current to go through the tunnel junction. For perpendicular MRAM, however, SOT driven switching of the free layer requires an external in-plane field, which poses limitation for viability in practical applications. Here we demonstrate field-free magnetization switching of a perpendicular magnet by utilizing an Iridium (Ir) layer. The Ir layer not only provides SOTs via spin Hall effect, but also induce interlayer exchange coupling with an in-plane magnetic layer that eliminates the need for the external field. Such dual functions of the Ir layer allows future build-up of magnetoresistive stacks for memory and logic applications. Experimental observations show that the SOT driven field-free magnetization reversal is characterized as domain nucleation and expansion. Micromagnetic modeling is carried out to provide in-depth understanding of the perpendicular magnetization reversal process in the presence of an in-plane exchange coupling field.