Investigation of Interfacial magnetic properties of novel oxide/ferromagnet heterostructures

Existing Si based memory technologies (for example static random-access memory , SRAM and dynamic random access memory, DRAM) are constantly facing challenges due to scaling, dynamic power loss as well as increasing speed gap between processor, memory unit and storage unit. To circumvent these problems, and to fulfill the future global data demand, emerging memory devices are being investigated. Among the different emerging memory devices, spintronic memory devices such as spin-transfer torque magnetic random-access memory (STT-MRAM) and spin-orbit torque MRAM (SOT-MRAM) are the leading contender to their unique set of characteristics.

However, in these spintronic memory devices, namely, STT-MRAM, SOT-MRAM, domain-wall MRAM (DW-MRAM), the writing[1], [2], reading[3] and retention[4] functionalities mainly originate from a magnetic tunnel junction (MTJ). Therefore, studying the interfacial magnetic properties of the novel oxide/ferromagnet heterostructure is important to find a new class of materials to further improve the performance of the devices.

The project will be mainly centered on deposition of these heterostructure by sputtering and characterizing magnetic properties (by VSM, MOKE etc.) chemical composition and structural properties by (XRD, XPS, SIMS etc). Depending on the progress of the project and success the experimental result will be compared by the result from ab-initio simulation. The student should have a strong interest in doing extensive literature surveys to find potentially interesting heterostructurs, knowledge on spintronics and nano-magnetism, and a skill of data analysis.

[1]      1) T. Kishi et al., “Lower-current and fast switching of a perpendicular TMR for high speed and high density spin-transfer-torque MRAM,” 2008 IEEE International Electron Devices Meeting, pp. 1–4, Dec. 2008.

[2]     2) S. Ikeda et al., “A perpendicular-anisotropy CoFeB-MgO magnetic tunnel junction.,” Nat Mater, vol. 9, pp. 721–724, Sep. 2010.

[3]     3) W. Butler, X.-G. Zhang, T. Schulthess, and J. MacLaren, “Spin-dependent tunneling conductance of Fe|MgO|Fe sandwiches,” Phys Rev B, vol. 63, no. 5, pp. 1–12, Jan. 2001.

[4]     4) H. X. Yang, M. Chshiev, B. Dieny, J. H. Lee, A. Manchon, and K. H. Shin, “First-principles investigation of the very large perpendicular magnetic anisotropy at Fe|MgO and Co|MgO interfaces,” Phys Rev B Condens Matter Mater Phys, vol. 84, no. 5, pp. 1–5, 2011.