講演情報
[17a-M_374-2]Magnetic tunnel junctions using a high entropy oxide barrier, LiTiMgAlGaO
〇(P)Rombang Rizky Sihombing1, Thomas Scheike1, Jun Uzuhashi1, Hideyuki Yasufuku1, Tadakatsu Ohkubo1, Zhenchao Wen1, Seiji Mitani1,2, Hiroaki Sukegawa1 (1.NIMS, 2.Univ. Tsukuba)
キーワード：
Tunnel Magnetoresistance、High entropy oxide barrier、Low barrier height
High-entropy materials, which are typically composed of five or more elements and are characterized by high mixing entropy, have attracted increasing attention due to the rapid emergence of new phases in functional materials [1]. High-entropy oxides (HEOs) are expected to realize their potential for electronic functionalities in spintronics, since the oxygen lattice required for these functionalities remains intact despite cation-site disorder. Ultra-thin HEOs with rock-salt or spinel structures in a (001) orientation are promising barrier materials with good structurally stability and low band gap for a magnetic tunnel junction (MTJ), which will lead to giant tunnel magnetoresistance ratio, a low resistance area product, and a high interface perpendicular magnetic anisotropy (PMA) energy, which are essential for the high-density spintronic devices. In this study, we developed an HEO barrier with a composition with LiTiMgAlGaO(001) (hereafter, L5O) [2].
We confirmed that the L5O layers were epitaxially grown with highly (001)-orientation and an atomically homogeneous cation distribution. Due to the achievement of a structurally stable L5O layer with a chemically sharp interface with CFB, a high interface PMA energy of up to 0.8 erg/cm2 at the L5O/CoFeB interface after post-annealing at 250-350oC. A TMR ratio reached 84% at room temperature in the L5O-based MTJ. This relatively large TMR ratio indicates that the presence of the spin-dependent coherent tunneling mechanism is observed even in HEO-based barriers. In addition, the L5O barrier exhibits a low barrier height of less than 1 eV, which is half that of an MgO barrier. Our results demonstrate that HEO materials are promising barrier materials for future spintronic applications.
References: [1] B. Cantor et al., Mater. Sci. Eng. A 375–377, 213 (2004). [2] R. R. Sihombing et al., Mater. Today 88, 12 (2025).
We confirmed that the L5O layers were epitaxially grown with highly (001)-orientation and an atomically homogeneous cation distribution. Due to the achievement of a structurally stable L5O layer with a chemically sharp interface with CFB, a high interface PMA energy of up to 0.8 erg/cm2 at the L5O/CoFeB interface after post-annealing at 250-350oC. A TMR ratio reached 84% at room temperature in the L5O-based MTJ. This relatively large TMR ratio indicates that the presence of the spin-dependent coherent tunneling mechanism is observed even in HEO-based barriers. In addition, the L5O barrier exhibits a low barrier height of less than 1 eV, which is half that of an MgO barrier. Our results demonstrate that HEO materials are promising barrier materials for future spintronic applications.
References: [1] B. Cantor et al., Mater. Sci. Eng. A 375–377, 213 (2004). [2] R. R. Sihombing et al., Mater. Today 88, 12 (2025).