Laboratory for Micro- and Nanotechnology, Paul Scherrer Institute, 5232 Villigen PSI, Switzerland.
Institute of Nano Science and Technology, Phase-10, Sector-64, Mohali, Punjab-160062, India.
Nat Commun. 2017 May 22;8:15388. doi: 10.1038/ncomms15388.
Realization of long-range magnetic order in surface-supported two-dimensional systems has been challenging, mainly due to the competition between fundamental magnetic interactions as the short-range Kondo effect and spin-stabilizing magnetic exchange interactions. Spin-bearing molecules on conducting substrates represent a rich platform to investigate the interplay of these fundamental magnetic interactions. Here we demonstrate the direct observation of long-range ferrimagnetic order emerging in a two-dimensional supramolecular Kondo lattice. The lattice consists of paramagnetic hexadeca-fluorinated iron phthalocyanine (FeFPc) and manganese phthalocyanine (MnPc) molecules co-assembled into a checkerboard pattern on single-crystalline Au(111) substrates. Remarkably, the remanent magnetic moments are oriented in the out-of-plane direction with significant contribution from orbital moments. First-principles calculations reveal that the FeFPc-MnPc antiferromagnetic nearest-neighbour coupling is mediated by the Ruderman-Kittel-Kasuya-Yosida exchange interaction via the Au substrate electronic states. Our findings suggest the use of molecular frameworks to engineer novel low-dimensional magnetically ordered materials and their application in molecular quantum devices.
在表面支撑的二维系统中实现长程磁有序一直具有挑战性，主要是由于基本磁相互作用之间的竞争，如短程 Kondo 效应和自旋稳定的磁交换相互作用。在导电衬底上的含自旋分子为研究这些基本磁相互作用的相互作用提供了一个丰富的平台。在这里，我们展示了在二维超分子 Kondo 晶格中出现的长程亚铁磁有序的直接观察。该晶格由顺磁十六氟代铁酞菁（FeFPc）和锰酞菁（MnPc）分子组成，在单晶 Au(111)衬底上共组装成棋盘图案。值得注意的是，剩余磁矩沿垂直于平面的方向取向，轨道磁矩有显著贡献。第一性原理计算表明，FeFPc-MnPc 反铁磁最近邻耦合通过 Au 衬底电子态通过 Ruderman-Kittel-Kasuya-Yosida 交换相互作用来介导。我们的发现表明可以使用分子框架来设计新型的低维磁有序材料，并将其应用于分子量子器件。
