Enhanced tunnel magnetoresistance of Fe/MgGa2O4/Fe(001) magnetic tunnel junctions by interface-tuning with atomic-scale MgO insertion layers

IF 3.5 2区物理与天体物理 Q2 PHYSICS, APPLIED

Applied Physics Letters Pub Date : 2025-01-15 DOI:10.1063/5.0247660

Rombang Rizky Sihombing, Thomas Scheike, Jun Uzuhashi, Tadakatsu Ohkubo, Zhenchao Wen, Seiji Mitani, Hiroaki Sukegawa

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引用次数: 0

Abstract

We demonstrate a significant effect of atomic-scale MgO insertion layers on the tunnel magnetoresistance (TMR) in epitaxial magnetic tunnel junctions (MTJs) using a small bandgap oxide MgGa2O4. An enhanced TMR ratio of 151% at room temperature (resistance area product, RA: 23 kΩ ⋅ μm2) and 291% at 5 K (RA: 26 kΩ ⋅ μm2) were observed using 0.3 nm MgO insertion layers at the bottom and top barrier interfaces in Fe/MgGa2O4/Fe(001) MTJs with a total barrier thickness of 2.3 nm. The TMR showed a strong MgO thickness dependence. Microstructure analyses revealed that after MgO insertion, a homogeneous rock-salt structured Mg0.55Ga0.45O(001) barrier is formed, which differs from the nominal spinel crystal MgGa2O4. Elemental mapping of the MTJ showed that Ga diffusion into the adjacent Fe can be effectively suppressed while maintaining perfect lattice-matching at the Fe/barrier interfaces, thereby improving effective tunneling spin polarization through the barrier. The RA of the Mg0.55Ga0.45O (2.3 nm) MTJ is smaller than that of a comparable MgAl2O4 barrier (2.3 nm), thanks to the lower barrier height of the Mg0.55Ga0.45O as confirmed by the current–voltage characteristics.

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原子尺度MgO插入层界面调谐增强Fe/MgGa2O4/Fe（001）磁性隧道结的隧道磁阻

我们展示了原子尺度氧化镁插入层对使用小带隙氧化物 MgGa2O4 的外延磁性隧道结 (MTJ) 中隧道磁阻 (TMR) 的显著影响。在总阻挡层厚度为 2.3 nm 的 Fe/MgGa2O4/Fe(001) MTJ 中，在底部和顶部阻挡层界面使用 0.3 nm 的氧化镁插入层，室温下的隧道磁阻比提高了 151%（电阻面积积，RA：23 kΩ ⋅ μm2），在 5 K 下提高了 291%（电阻面积积，RA：26 kΩ ⋅ μm2）。TMR 显示出强烈的氧化镁厚度依赖性。显微结构分析表明，在插入氧化镁后，形成了均匀的岩盐结构 Mg0.55Ga0.45O(001)势垒，这与标称的尖晶石晶体 MgGa2O4 不同。MTJ 的元素图谱显示，在保持铁/势垒界面完美晶格匹配的同时，镓向邻近铁的扩散可以被有效抑制，从而提高了通过势垒的有效隧道自旋极化。电流-电压特性证实，由于 Mg0.55Ga0.45O 的势垒高度较低，Mg0.55Ga0.45O（2.3 nm）MTJ 的 RA 小于同类 MgAl2O4 势垒（2.3 nm）的 RA。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Applied Physics Letters 物理-物理：应用

CiteScore

6.40

自引率

10.00%

发文量

1821

审稿时长

1.6 months

期刊介绍： Applied Physics Letters (APL) features concise, up-to-date reports on significant new findings in applied physics. Emphasizing rapid dissemination of key data and new physical insights, APL offers prompt publication of new experimental and theoretical papers reporting applications of physics phenomena to all branches of science, engineering, and modern technology. In addition to regular articles, the journal also publishes invited Fast Track, Perspectives, and in-depth Editorials which report on cutting-edge areas in applied physics. APL Perspectives are forward-looking invited letters which highlight recent developments or discoveries. Emphasis is placed on very recent developments, potentially disruptive technologies, open questions and possible solutions. They also include a mini-roadmap detailing where the community should direct efforts in order for the phenomena to be viable for application and the challenges associated with meeting that performance threshold. Perspectives are characterized by personal viewpoints and opinions of recognized experts in the field. Fast Track articles are invited original research articles that report results that are particularly novel and important or provide a significant advancement in an emerging field. Because of the urgency and scientific importance of the work, the peer review process is accelerated. If, during the review process, it becomes apparent that the paper does not meet the Fast Track criterion, it is returned to a normal track.