講演情報
[11a-E208-8]Enhanced Tunnel Magnetoresistance of High Entropy LiTiMgAlGaO Barrier-Based Magnetic Tunnel Junctions
〇(P)Rombang Rizky Sihombing1, Thomas Scheike1,3, Jun Uzuhashi1, Tadakatsu Ohkubo1, Zhenchao Wen1, Seiji Mitani1,2, Hiroaki Sukegawa1,2 (1.NIMS, 2.Univ. Tsukuba, 3.AIST)
キーワード：
Tunnel magnetoresistance、High entropy oxides、Low barrier height
Magnetoresistive random-access memory (MRAM) cells and tunnel magnetoresistive (TMR) heads in hard disk drives are major examples of spintronic applications that utilize magnetic tunnel junctions (MTJs). Toward future ultra-high-density HDD and MRAM applications, it is required to reduce the resistance-area product (RA) while maintaining the barrier thickness. Recently, a high-entropy oxide barrier, LiTiMgAlGaO (L5O), was developed as an MTJ barrier and exhibited a TMR ratio of 84% at room temperature (RT) using a sputtered Fe/MgO/L5O/MgO/Fe structure. Notably, the effective barrier height of the L5O barrier was half that of an MgO barrier [1]. In this study, we report enhanced TMR ratios of an L5O-based MTJ using MgO insertions deposited by electron-beam (EB) evaporation.
The bottom MgO, L5O, and top MgO show highly (001) oriented epitaxial growth, which was revealed by reflection high-energy electron diffraction and cross-sectional scanning transmission electron microscopy (STEM). We observed a TMR ratio of up to 131% (242%) at RT (at low temperature), which is 1.6 times higher than the previous ratio of sputtered MgO insertions [1]. This indicates that EB evaporation for the MgO significantly improved the interfacial crystallinity and sharpness. STEM images also revealed a lattice-matched Fe/Mg-rich L5O/Fe(001) structure, indicating the occurrence of elemental rearrangements near the interfaces. These results suggest that improvements to the magnetic layer/barrier interface structures could lead to further TMR enhancements for high-entropy barrier-based MTJs.
The bottom MgO, L5O, and top MgO show highly (001) oriented epitaxial growth, which was revealed by reflection high-energy electron diffraction and cross-sectional scanning transmission electron microscopy (STEM). We observed a TMR ratio of up to 131% (242%) at RT (at low temperature), which is 1.6 times higher than the previous ratio of sputtered MgO insertions [1]. This indicates that EB evaporation for the MgO significantly improved the interfacial crystallinity and sharpness. STEM images also revealed a lattice-matched Fe/Mg-rich L5O/Fe(001) structure, indicating the occurrence of elemental rearrangements near the interfaces. These results suggest that improvements to the magnetic layer/barrier interface structures could lead to further TMR enhancements for high-entropy barrier-based MTJs.