Electric-Field-Controlled MRAM:
Physics and Applications
James Lourembam and Jiancheng Huang
Abstract This chapter provides a comprehensive overview of the electric-field (or
voltage) control of magnetic anisotropy, an emerging concept for the next-generation
memory device. This approach has many technological appeals as it can enable ultralow-latency data transfer and ultra-low power electronics. The underlying mechanisms governing magnetization switching from an applied electric-field are interfacial spin-charge coupling and Larmor precession. This allows for electric-fielddriven MRAM as opposed to current-driven in conventional spin-torque MRAM.
An exhaustive discussion in particular relevance to industry-friendly materials is
provided in this chapter. The challenges in implementation and possible solutions
including field-free approach are discussed. The chapter summarises the experimental and theoretical progress in electric-field-controlled MRAM, discusses our
current understanding, and finally presents the prospects of utilising this approach.
1 Introduction
Magnetoresistive random-access memory (MRAM) utilises magnetic tunnel junctions (MTJ), where data bits are written and stored by manipulating the relative
magnetization orientation of the ferromagnetic layers, which are separated by an
oxide barrier. Manipulating the storage layer in MTJ was initially achieved through
Oersted field generated from the current passing through the bit line [1]. However,
such a scheme though still in production now does not favor device scaling. The
next generation of MRAM was realized through spin-transfer-torque (STT) where
writing is achieved by sending a current through the MTJ along with transfer of
J. Lourembam (B)
Institute of Materials Research and Engineering, Agency for Science Technology and Research
(A*STAR), #08-03, 2 Fusionopolis Way, Innovis 138634, Singapore
e-mail: james_lourembam@imre.a-star.edu.sg
J. Huang
Taiwan Semiconductor Manufacturing Company, 168 Park Ave. 2, Hsinchu Science Park,
Hsinchu 300-75, Taiwan ROC
e-mail: huangjia@tsmc.com
© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2021
W. S. Lew et al. (eds.), Emerging Non-volatile Memory Technologies,
https://doi.org/10.1007/978-981-15-6912-8_4
149
Physics and Applications
James Lourembam and Jiancheng Huang
Abstract This chapter provides a comprehensive overview of the electric-field (or
voltage) control of magnetic anisotropy, an emerging concept for the next-generation
memory device. This approach has many technological appeals as it can enable ultralow-latency data transfer and ultra-low power electronics. The underlying mechanisms governing magnetization switching from an applied electric-field are interfacial spin-charge coupling and Larmor precession. This allows for electric-fielddriven MRAM as opposed to current-driven in conventional spin-torque MRAM.
An exhaustive discussion in particular relevance to industry-friendly materials is
provided in this chapter. The challenges in implementation and possible solutions
including field-free approach are discussed. The chapter summarises the experimental and theoretical progress in electric-field-controlled MRAM, discusses our
current understanding, and finally presents the prospects of utilising this approach.
1 Introduction
Magnetoresistive random-access memory (MRAM) utilises magnetic tunnel junctions (MTJ), where data bits are written and stored by manipulating the relative
magnetization orientation of the ferromagnetic layers, which are separated by an
oxide barrier. Manipulating the storage layer in MTJ was initially achieved through
Oersted field generated from the current passing through the bit line [1]. However,
such a scheme though still in production now does not favor device scaling. The
next generation of MRAM was realized through spin-transfer-torque (STT) where
writing is achieved by sending a current through the MTJ along with transfer of
J. Lourembam (B)
Institute of Materials Research and Engineering, Agency for Science Technology and Research
(A*STAR), #08-03, 2 Fusionopolis Way, Innovis 138634, Singapore
e-mail: james_lourembam@imre.a-star.edu.sg
J. Huang
Taiwan Semiconductor Manufacturing Company, 168 Park Ave. 2, Hsinchu Science Park,
Hsinchu 300-75, Taiwan ROC
e-mail: huangjia@tsmc.com
© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2021
W. S. Lew et al. (eds.), Emerging Non-volatile Memory Technologies,
https://doi.org/10.1007/978-981-15-6912-8_4
149