论文标题
Ultrathin Ferrimagnetic nico $ _2 $ o $ _4 $胶片中的异常大厅效应和垂直磁各向异性
Anomalous Hall Effect and Perpendicular Magnetic Anisotropy in Ultrathin Ferrimagnetic NiCo$_2$O$_4$ Films
论文作者
论文摘要
反尖晶石的铁磁性nico $ _2 $ o $ _4 $具有高磁性库丽温度$ T_C $，高自旋极化和应变可触发的磁动率。了解NICO $ _2 $ o $ _4 $薄膜中这些有趣的磁性特性的厚度缩放限制对于它们在纳米级Spintronic应用中的实现至关重要。在这项工作中，我们报告了外延（001）NICO $ _2 $ o $ o $ _4 $ ticles in Mgal $ _2 $ _2 $ o $ $ _4 $ substrates in Ultrathin loce of Ultrathin limit中的非常规（001）的非常规的磁转运属性。异常大厅效应的测量表明，薄膜的垂直磁各向异性强，降低至1.5元单元（1.2 nm），而3个单位电池的$ t_c $保持在300 K以上。杂质散射与固有性浆果曲率之间的竞争效应，后者消失在厚度驱动的金属 - 绝缘体过渡上。我们的研究揭示了膜厚度在调整电荷相关性，浆果相效应，旋转轨道相互作用和杂质散射的相对强度中的关键作用，从而为设计可扩展的外观磁性隧道连接和使用NICO $ $ _2 $ o $ o $ _4 $设计的可扩展外延磁性隧道连接和感测设备提供了重要的材料信息。
The inverse spinel ferrimagnetic NiCo$_2$O$_4$ possesses high magnetic Curie temperature $T_C$, high spin polarization, and strain-tunable magnetic anisotropy. Understanding the thickness scaling limit of these intriguing magnetic properties in NiCo$_2$O$_4$ thin films is critical for their implementation in nanoscale spintronic applications. In this work, we report the unconventional magnetotransport properties of epitaxial (001) NiCo$_2$O$_4$ films on MgAl$_2$O$_4$ substrates in the ultrathin limit. Anomalous Hall effect measurements reveal strong perpendicular magnetic anisotropy for films down to 1.5 unit cell (1.2 nm), while $T_C$ for 3 unit cell and thicker films remains above 300 K. The sign change in the anomalous Hall conductivity ($σ_{xy}$) and its scaling relation with the longitudinal conductivity ($σ_{xx}$) can be attributed to the competing effects between impurity scattering and band intrinsic Berry curvature, with the latter vanishing upon the thickness driven metal-insulator transition. Our study reveals the critical role of film thickness in tuning the relative strength of charge correlation, Berry phase effect, spin orbit interaction, and impurity scattering, providing important material information for designing scalable epitaxial magnetic tunnel junctions and sensing devices using NiCo$_2$O$_4$.
