Perpendicular magnetic tunnel junctions (p-MTJs) switched utilizing bipolar electric fields have extensive applications in energy-efficient memory and logic devices. Voltage-controlled magnetic anisotropy linearly lowers the energy barrier of the ferromagnetic layer via the electric field effect and efficiently switches p-MTJs only with a unipolar behavior. Here, we demonstrate a bipolar electric field effect switching of 100 nm p-MTJs with a synthetic antiferromagnetic free layer through voltage-controlled exchange coupling (VCEC). The switching current density, ∼1.1 × 105 A/cm2, is 1 order of magnitude lower than that of the best-reported spin-transfer torque devices. Theoretical results suggest that the electric field induces a ferromagnetic-antiferromagnetic exchange coupling transition of the synthetic antiferromagnetic free layer and generates a fieldlike interlayer exchange coupling torque, which causes the bidirectional magnetization switching of p-MTJs. These results could eliminate the major obstacle in the development of spin memory devices beyond their embedded applications.
Bibliographical noteFunding Information:
This work was supported in part by C-SPIN, one of six centers of STARnet, and is currently supported by ASCENT, one of six centers of JUMP, a Semiconductor Research Corporation program that is sponsored by MARCO and DARPA. Portions of this work were conducted in the Minnesota Nano Center, which is supported by the National Science Foundation through the National Nano Coordinated Infrastructure Network (NNCI) under Award ECCS-1542202. We would like to thank Dr. Paul M. Haney from the National Institute of Standards and Technology (NIST) for valuable discussions and suggestions, and Prof. Paul M. Voyles from University of Wisconsin─Madison for providing the STEM images.
- Magnetic Tunnel Junctions
- Synthetic antiferromagnetic free layer
- Voltage-Controlled Exchange Coupling (VCEC)
PubMed: MeSH publication types
- Journal Article