Insertion Trade-off Effects on the Spin-Transfer Torque Memory Explored byIn SituX-ray

Akhil K. Ramesh, Kuan Ming Chen, Yi Jan Lin, Pushpapraj Singh, Jeng Hua Wei, Yu Chen Hsin, Chih I. Wu, Yuan Chieh Tseng*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

Magnetoresistive random-access memory (MRAM) relies on magnetic tunnel junctions (MTJs) comprising heterostructures of CoFeB/MgO/CoFeB. Nonetheless, the dielectric breakdown of MgO limits the lifespan of MRAM devices. In the current study, we terminated MgO with a Mg surface facing the CoFeB free layer to reduce the mismatch in band alignment across the barrier. The Mg-modified interface was shown to enhance the breakdown voltage while reducing the switching current and asymmetric switching behavior, with a moderate sacrifice of perpendicular magnetic anisotropy, tunneling magnetoresistance, and resistance-area product. This performance trade-off was observed in all MTJs, regardless of cell size (180, 130, and 80 nm; each size has been tested with at least 20 cells). Visualization of the proposed junctionviain situX-ray absorption spectroscopy proved effective in elucidating the reconstruction of the interface within the context of energy barrier height, asymmetric switching behavior, and the voltage-driven movement of oxygen ions. A spin-dependent band diagram was constructed to correlate the tunneling/switching properties of the MTJ with such a trade-off scenario. The atomistic simulation of the magnetic properties revealed that Mg termination lowered the switching energy barrier with an effective domain wall motion within the CoFeB free layer.

Original languageEnglish
Pages (from-to)4047-4055
Number of pages9
JournalACS Applied Electronic Materials
Volume3
Issue number9
DOIs
StatePublished - 28 Sep 2021

Keywords

  • atomistic simulation
  • interface
  • MRAM
  • spin-transfer torque
  • spintronics
  • X-ray absorption spectroscopy

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