R&D: Demonstration of Spin Transfer Torque Magnetic Recording

Applied Physics Letters has published an article written by Jeongmin Hong, Xin Li, School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, China, OukJae Lee, Center for Spintronics, Korea Institute of Science and Technology, Seoul 02529, South Korea, Weicheng Tian, School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, China, Sakhrat Khizroev, Department of Electrical and Computer Engineering, University of Miami, Coral Gables, Florida 33199, USA, Jeffrey Bokor, EECS, UC Berkeley, Berkeley, California 94720, USA, and Long You, School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, China.

Abstract: ”In the magnetic hard disk drive industry, a continuous increase in the recording density requires higher anisotropy media in order to maintain thermal stability. However, further advances by scaling have run into a stumbling block due to limitations on the required magnetic fields, particularly for writing, which is currently being addressed by alternative approaches such as heat-assisted magnetic recording and microwave-assisted magnetic recording technologies. In this work, we investigate and demonstrate another alternative approach which is based on the effect of the spin transfer torque (STT). The approach uses tunneling spin-polarized currents, instead of magnetic fields, between a nanoscale magnetic probe and a magnetic recording media, both with a perpendicular anisotropy. Writing is performed by spin polarized electrons injected from the probe into the media, due to the STT effect. Reading is produced by the tunneling magnetoresistance (TMR) effect between the two magnetic layers, in the probe writer and the media substrate, respectively. The energy-efficient switching, with an energy of 3.1 MA/cm², is confirmed through the TMR and the magneto-optical Kerr effect. The demonstrated STT-based magnetic recording overcomes the magnetic field limitations to both writing and reading and thus paves the way for the next-generation energy-efficient and extremely high-density recording.”

This work was supported by the National Natural Science Foundation of China under Award No. 61674062. This work was also supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering under Contract No. DE-AC02-05CH11231. The authors acknowledge financial support from the National Science Foundation (NSF) Center for Energy Efficient Electronics Science (E3S) under Award No. 0939514 and the Air Force Office of Scientific Research (AFOSR) Nos. FA9550-18-1-0527 and NSF-ECCS-1810270.