Antiferromagnetically coupled magnetic skyrmions are considered ideal candidates for high-density information carriers. This is due to the suppressed skyrmion Hall effect compared to conventional skyrmions and a smaller size due to the cancellation of some contributions to the magnetostatic dipolar fields. By means of systematic first-principles calculations based on density functional theory we search for suitable materials that can host antiferromagnetically coupled skyrmions. We concentrate on fcc-stacked (111)-oriented metallic $Z/\mathrm{Co}/\mathrm{Pt}$ ($Z=4d$ series: Y–Pd, the noble metals: Cu, Ag, Au, post-noble metals: Zn and Cd) magnetic multilayers of films of monatomic thickness. We present quantitative trends of magnetic properties: magnetic moments, interlayer exchange coupling, spin stiffness, Dzyaloshinskii-Moriya interaction, magnetic anisotropy, and the critical temperature. We show that some of the $Z$ elements (Zn, Y, Zr, Nb, Tc, Ru, Rh, and Cd) can induce antiferromagnetic interlayer coupling between the magnetic Co layers, and that they influence the easy magnetization axis. Employing a multiscale approach, we transfer the micromagnetic parameters determined from ab initio to a micromagnetic energy functional and search for one-dimensional spin-spiral solutions and two-dimensional skyrmions. We determine the skyrmion radius by numerically solving the equation of the skyrmion profile. We found an analytical expression for the skyrmion radius that covers our numerical results and is valid for a large regime of micromagnetic parameters. Based on this expression we have proposed a model that allows to extrapolate from the ab initio results of monatomic films to multilayers with Co films consisting of several atomic layers containing $10\text{−}\mathrm{nm}$ skyrmions. We found thickness regimes where tiny changes of the film thickness may alter the skyrmion radius by orders of magnitude. We estimated the skyrmion size as function of temperature and found that the size can easily double going from cryogenic to room temperature. We suggest promising material systems for ferromagnetically and antiferromagnetically coupled spin-spiral and skyrmion systems.

中文翻译：

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Co / Pt基多层膜中FM / AFM耦合天体的材料系统

反铁磁耦合的磁性天体被认为是高密度信息载体的理想候选者。这是由于与传统的天蝎子相比，天蝎子的霍尔效应得到抑制，并且由于消除了对静磁偶极子场的某些贡献，因此体积更小。通过基于密度泛函理论的系统第一性原理计算，我们寻找可以容纳反铁磁耦合天体的合适材料。我们专注于面向fcc堆叠（111）的金属$ž/\mathrm{有限公司}/铂$ （$ž=4d$系列：Y–Pd，贵金属：Cu，Ag，Au，后贵金属：Zn和Cd）单原子厚度薄膜的磁性多层。我们提出了磁性的定量趋势：磁矩，层间交换耦合，自旋刚度，Dzyaloshinskii-Moriya相互作用，磁各向异性和临界温度。我们显示了一些$ž$元素（Zn，Y，Zr，Nb，Tc，Ru，Rh和Cd）会引起磁性Co层之间的反铁磁层间耦合，并影响易磁化轴。我们采用多尺度方法，将从头确定的微磁参数传递给微磁能函数，并搜索一维自旋螺旋解和二维天体离子。我们通过数值求解天体离子轮廓方程来确定天体离子半径。我们找到了一个关于天蝎子半径的解析表达式，该表达式涵盖了我们的数值结果，并且对于大范围的微磁参数有效。基于此表达式，我们提出了一个模型，该模型允许从头算起进行推断 原子膜形成多层Co膜的结果 $10\text{-}\mathrm{纳米}$天空。我们发现了一些厚度范围，其中薄膜厚度的微小变化可能会改变数个星标半径。我们估计了天rm子的尺寸随温度的变化，发现从低温到室温，尺寸很容易翻倍。我们建议有前途的材料系统用于铁磁和反铁磁耦合的自旋螺旋和天体离子系统。