Lv Hua, Huang Xiao Chun, Zhang Kelvin Hong Liang, Bierwagen Oliver, Ramsteiner Manfred
Paul-Drude-Institut für Festkörperelektronik, Leibniz-Institut im Forschungsverbund Berlin e. V., Hausvogteiplatz 5-7, 10117, Berlin, Germany.
State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, P. R. China.
Adv Sci (Weinh). 2023 Oct;10(28):e2302956. doi: 10.1002/advs.202302956. Epub 2023 Aug 2.
Their high tunability of electronic and magnetic properties makes transition-metal oxides (TMOs) highly intriguing for fundamental studies and promising for a wide range of applications. TMOs with strong ferrimagnetism provide new platforms for tailoring the anomalous Hall effect (AHE) beyond conventional concepts based on ferromagnets, and particularly TMOs with perpendicular magnetic anisotropy (PMA) are of prime importance for today's spintronics. This study reports on transport phenomena and magnetic characteristics of the ferrimagnetic TMO NiCo O (NCO) exhibiting PMA. The entire electrical and magnetic properties of NCO films are strongly correlated with their conductivities governed by the cation valence states. The AHE exhibits an unusual sign reversal resulting from a competition between intrinsic and extrinsic mechanisms depending on the conductivity, which can be tuned by the synthesis conditions independent of the film thickness. Importantly, skew-scattering is identified as an AHE contribution for the first time in the low-conductivity regime. Application wise, the robust PMA without thickness limitation constitutes a major advantage compared to conventional PMA materials utilized in today's spintronics. The great potential for applications is exemplified by two proposed novel device designs consisting only of NCO films that open a new route for future spintronics, such as ferrimagnetic high-density memories.
过渡金属氧化物（TMOs）具有高度可调节的电子和磁性特性，这使其在基础研究中极具吸引力，并在广泛的应用领域展现出广阔前景。具有强亚铁磁性的TMOs为超越基于铁磁体的传统概念来调控反常霍尔效应（AHE）提供了新平台，特别是具有垂直磁各向异性（PMA）的TMOs对于当今的自旋电子学至关重要。本研究报告了呈现PMA的亚铁磁性TMO NiCo O（NCO）的输运现象和磁特性。NCO薄膜的整体电学和磁学性质与其由阳离子价态控制的电导率密切相关。AHE表现出一种不寻常的符号反转，这是由取决于电导率的本征和非本征机制之间的竞争导致的，电导率可通过与薄膜厚度无关的合成条件进行调节。重要的是，在低电导率 regime中，首次确定了斜散射是AHE的一个贡献因素。在应用方面，与当今自旋电子学中使用的传统PMA材料相比，不受厚度限制的强大PMA构成了一个主要优势。仅由NCO薄膜组成的两种新型器件设计展示了巨大的应用潜力，为未来的自旋电子学开辟了一条新途径，例如亚铁磁性高密度存储器。
