Dr. Goran Mihajlović
Senior Technologist, Western Digital Corporation, San Jose, CA 95119
Date & Time: 11:00 - 12:00, April 18th (Fri), 2025.
Place: 2nd Conference Room, Main Bldg., Sengen.
Physics and characterization of perpendicular STT MRAM cells
Dr. Goran Mihajlović
Senior Technologist, Western Digital Corporation, San Jose, CA 95119
Abstract:
Spin torque magnetoresistive random access memory (STT MRAM) is an emerging memory technology with unique physical properties that can provide non-volatility concurrently with low power, high speed and high endurance operation [1]. STT MRAM stores, writes and reads the information using magnetic tunnel junctions (MTJs) that can be integrated into a standard back-end-of-line CMOS process flow as well as fabricated as dense cross-point arrays of 1 selector 1 MTJ cells [2], thus potentially replacing SRAM, DRAM and Flash in a wide range of embedded and stand-alone memory applications. In this seminar I will describe basic physics of STT MRAM cell operation and present recent experimental, theoretical, and modeling results from Western Digital in this field. In particular, I will describe our work on optimization of free layer (FL) materials for improving thermal stability [3] and lowering switching currents [4], characterization of FL magnetization reversal [5] and damping [6] on the cell level, development of MTJs with dual reference layers that enable ultra-low switching currents [7], enhancement of write margin using thick MgO cap layers [8], characterization and physical understanding of cell endurance [9] and size dependence of MRAM read signals down to sub-20 nm diameters [10]. I will end by discussing the remaining challenges and further research opportunities in this field.
REFERENCES
[1] D. C. Worledge et al., Nat. Rev. Electr. Eng. 1, 730 (2024).
[2] S. M. Seo et al., IEDM 10.1.1-10.1.4 (2022).
[3] G. Mihajlović et al., Appl. Phys. Lett. 117, 242404 (2020).
[4] T. Santos et al., J. App. Phys. 128, 113904 (2020).
[5] H. J. Richter et al., AIP Advances 13, 025013 (2023).
[6] H. J. Richter et al., J. Appl. Phys. 136, 113902 (2024).
[7] G. Mihajlović et al., Appl. Phys. Lett. 126, 022403 (2025).
[8] G. Mihajlović et al., AIP Advances 14, 115224 (2024).
[9] J. Gibbons et al., submitted.
[10] G. Mihajlović et al., submitted.
REFERENCES
[1] D. C. Worledge et al., Nat. Rev. Electr. Eng. 1, 730 (2024).
[2] S. M. Seo et al., IEDM 10.1.1-10.1.4 (2022).
[3] G. Mihajlović et al., Appl. Phys. Lett. 117, 242404 (2020).
[4] T. Santos et al., J. App. Phys. 128, 113904 (2020).
[5] H. J. Richter et al., AIP Advances 13, 025013 (2023).
[6] H. J. Richter et al., J. Appl. Phys. 136, 113902 (2024).
[7] G. Mihajlović et al., Appl. Phys. Lett. 126, 022403 (2025).
[8] G. Mihajlović et al., AIP Advances 14, 115224 (2024).
[9] J. Gibbons et al., submitted.
[10] G. Mihajlović et al., submitted.
(Contact)
Tomoya Nakatani, Principal Researcher, Magnetic Functional Device Group, Research Center for Magnetic and Spintronic Materials.
E-mail: NAKATANI.Tomoya[at]nims.go.jp
E-mail: NAKATANI.Tomoya[at]nims.go.jp