Magnetic skyrmions are promising information carriers for dense and energy-efficient information storage owing to their small size, low driving-current density, and topological stability.*
Electrical detection of skyrmions is a crucial requirement to drive skyrmion devices toward applications. The use of a magnetic tunnel junction (MTJ) is commonly suggested for this purpose as MTJs are key spintronic devices for large-scale commercialization that can convert magnetic textures into electrical signals. To date, however, it has been challenging to realize skyrmions in MTJs due to incompatibility between standard skyrmion materials and highly efficient MTJ electrodes.*
In the article “Electrical Detection of Magnetic Skyrmions in a Magnetic Tunnel Junction” Yao Guang, Like Zhang, Junwei Zhang, Yadong Wang, Yuelei Zhao, Riccardo Tomasello, Senfu Zhang, Bin He, Jiahui Li, Yizhou Liu, Jiafeng Feng, Hongxiang Wei, Mario Carpentieri, Zhipeng Hou, Junming Liu, Yong Peng, Zhongming Zeng, Giovanni Finocchio, Xixiang Zhang, John Michael David Coey, Xiufeng Han and Guoqiang Yu report a material stack combining magnetic multilayers, which host 100 nm scale skyrmions, with a perpendicularly magnetized MTJ.*
In their article the authors describe how they combined electrical transport measurements with direct imaging of magnetic texture by magnetic force microscopy (MFM).*
The materials stack is designed to imprint the magnetic domain pattern of the multilayer into the MTJ’s free layer via magnetostatic interactions. The evolution of the magnetic domain pattern is revealed by MFM, which shows that skyrmions can be stabilized in the fabricated MTJ with an appropriate magnetic field.*
The realization of electrical reading of skyrmions using an MTJ opens the route to all-electrical skyrmion devices, which is a crucial step for the development of skyrmionics. *
The technique reported by Yao Guang et al. can further advance the simultaneous optimization of the parameters for skyrmion stabilization and MTJ read-out, thus opening a way to realize skyrmion-based devices such as racetrack memory, logic gates, oscillators, detectors,artificial synapses for neuromorphic computing, and reshuffling devices with an efficient CMOS compatible read-out mechanism.*
The magnetic response was studied using NANOSENSORS™ SuperSharpSilicon™ High Resolution Magnetic Force Microscopy AFM Probes ( SSS-MFMR typical force constant 2.8 N/m) in-phase mode and with a lift height of 30 nm. The transport measurements of MTJ were performed in the PPMS or the MFM that is upgraded with electrical measurement equipment.*
Figure 4 from Yao Guang et al. “Electrical Detection of Magnetic Skyrmions in a Magnetic Tunnel Junction”:
Electrical detection of magnetic skyrmions in the MTJ. a–g) MFM images of domain structures in the MTJ junction with tCoFeB = 1.5 nm and junction size of 3 µm at different magnetic fields. h) MFM phase data for the skyrmion #2 in (f) and the analytical skyrmion profile obtained from Equation (3). i) The resistances of the MTJ corresponding to MFM images in (a–g). The resistance plotted is obtained by averaging the resistance measured before and after the MFM imaging. The dashed line indicates the resistance for the single domain state at a magnetic field of 110 mT (state d).
*Yao Guang, Like Zhang, Junwei Zhang, Yadong Wang, Yuelei Zhao, Riccardo Tomasello, Senfu Zhang, Bin He, Jiahui Li, Yizhou Liu, Jiafeng Feng, Hongxiang Wei, Mario Carpentieri, Zhipeng Hou, Junming Liu, Yong Peng, Zhongming Zeng, Giovanni Finocchio, Xixiang Zhang, John Michael David Coey, Xiufeng Han and Guoqiang Yu
Electrical Detection of Magnetic Skyrmions in a Magnetic Tunnel Junction
Advanced Electronic Materials, Volume 9, Issue 1, January 2023, 2200570
DOI: https://doi.org/10.1002/aelm.202200570
Open Access: The article “Electrical Detection of Magnetic Skyrmions in a Magnetic Tunnel Junction” by Yao Guang, Like Zhang, Junwei Zhang, Yadong Wang, Yuelei Zhao, Riccardo Tomasello, Senfu Zhang, Bin He, Jiahui Li, Yizhou Liu, Jiafeng Feng, Hongxiang Wei, Mario Carpentieri, Zhipeng Hou, Junming Liu, Yong Peng, Zhongming Zeng, Giovanni Finocchio, Xixiang Zhang, John Michael David Coey, Xiufeng Han and Guoqiang Yu is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit https://creativecommons.org/licenses/by/4.0/.