R&D: Enhanced Tunnel Magnetoresistance in Mn-based Perpendicular Magnetic Tunnel Junctions Utilizing Antiferromagnetically Coupled bcc-Co-based Interlayer

Applied Physics Letters has published an article written by Kazuya Z. Suzuki, WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan, and Center for Spintronics Research Network (CSRN), Tohoku University, Sendai 980-8577, Japan, Tomohiro Ichinose, WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan, Satoshi Iihama, WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan, and Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, Sendai 980-8578, Japan, Ren Monma, WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan, and Department of Applied Physics, Graduate School of Engineering, Tohoku University, Sendai 980-8579, Japan, and Shigemi Mizukami, WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan, Center for Spintronics Research Network (CSRN), Tohoku University, Sendai 980-8577, Japan, and Center for Science and Innovation in Spintronics (CSIS), Core Research Cluster (CRC), Tohoku University, Sendai 980-8577, Japan.

Abstract: “High tunnel magnetoresistance (TMR) in perpendicular magnetic tunnel junctions (p-MTJs) with tetragonal Mn-based electrodes is expected to play a key role in the realization of practical high-density magnetic memories, advanced THz devices, and magnetic sensors. In this study, we demonstrated the use of bcc-Co-based alloys, such as bcc-Co and bcc-CoMn binary alloys, as antiferromagnetically coupled interlayers for MnGa-based p-MTJs. The interlayer of bcc-Co enhanced the TMR ratio of MnGa-based MTJs by 70% at 300 K and 145% at 10 K. Furthermore, the TMR ratio of the MTJ with the bcc-CoMn interlayer was enhanced up to 85 (209)% at 300 (10) K at a thickness of 0.8 nm. The enhancement in the TMRs can be attributed to the electronic band with the ?1 symmetry of the bcc-Co-based alloy. In addition, the Co-based interlayer supported the growth of a high-quality MgO barrier sufficient for sustaining the coherency of the tunnel electrons from the Bloch state in the ferromagnetic electrode. These results suggest that bcc-Co-based interlayers are promising interlayer materials for MnGa-based p-MTJs.“

We would like to thank Y. Kondo for his technical assistance. This work was partially supported by JST CREST (No. JPMJCR17J5).