Centro S3, Istituto Nanoscienze - CNR, via G. Campi 213/A, 41125 Modena, Italy.
Nanoscale. 2017 Dec 21;10(1):277-283. doi: 10.1039/c7nr06610d.
Lanthanides (Ln) bis-phthalocyanine (Pc), the so-called LnPcdouble decker, are a promising class of molecules with a well-defined magnetic anisotropy. In this work, we investigate the magnetic properties of LnPc molecules UHV-deposited on a graphene/Ni(111) substrate and how they modify when an Au layer is intercalated between Ni and graphene. X-ray absorption spectroscopy (XAS), and linear and magnetic circular dichroism (XLD and XMCD) were used to characterize the systems and probe the magnetic coupling between LnPc molecules and the Ni substrate through graphene, both gold-intercalated and not. Two types of LnPc molecules (Ln = Tb, Er) with a different magnetic anisotropy (easy-axis for Tb, easy-plane for Er) were considered. XMCD shows an antiferromagnetic coupling between Ln and Ni(111) even in the presence of the graphene interlayer. Au intercalation causes the vanishing of the interaction between Tb and Ni(111). In contrast, in the case of ErPc, we found that the gold intercalation does not perturb the magnetic coupling. These results, combined with the magnetic anisotropy of the systems, suggest the possible importance of the magnetic dipolar field contribution for determining the magnetic behaviour.
镧系元素（Ln）双酞菁（Pc），即所谓的 LnPc 双层，是一类具有明确磁各向异性的有前途的分子。在这项工作中，我们研究了在石墨烯/Ni(111)衬底上 UHV 沉积的 LnPc 分子的磁性特性，以及当在 Ni 和石墨烯之间插入 Au 层时它们如何发生变化。我们使用 X 射线吸收光谱（XAS）、线性和磁圆二色性（XLD 和 XMCD）来表征这些系统，并通过石墨烯探测 LnPc 分子与 Ni 衬底之间的磁耦合，包括 Au 插入和未插入的情况。我们考虑了两种具有不同磁各向异性（Tb 为易轴，Er 为易面）的 LnPc 分子（Ln = Tb、Er）。XMCD 显示 Ln 与 Ni(111)之间存在反铁磁耦合，即使存在石墨烯层间。Au 插入导致 Tb 与 Ni(111)之间的相互作用消失。相比之下，在 ErPc 的情况下，我们发现 Au 插入不会干扰磁耦合。这些结果，结合系统的磁各向异性，表明磁偶极场贡献对确定磁行为可能很重要。
