Avsar Ahmet, Cheon Cheol-Yeon, Pizzochero Michele, Tripathi Mukesh, Ciarrocchi Alberto, Yazyev Oleg V, Kis Andras
Electrical Engineering Institute, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, 1015, Switzerland.
Institute of Materials Science and Engineering, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, CH, 1015, Switzerland.
Nat Commun. 2020 Sep 23;11(1):4806. doi: 10.1038/s41467-020-18521-6.
Atomic-scale disorder in two-dimensional transition metal dichalcogenides is often accompanied by local magnetic moments, which can conceivably induce long-range magnetic ordering into intrinsically non-magnetic materials. Here, we demonstrate the signature of long-range magnetic orderings in defective mono- and bi-layer semiconducting PtSe by performing magnetoresistance measurements under both lateral and vertical measurement configurations. As the material is thinned down from bi- to mono-layer thickness, we observe a ferromagnetic-to-antiferromagnetic crossover, a behavior which is opposite to the one observed in the prototypical 2D magnet CrI. Our first-principles calculations, supported by aberration-corrected transmission electron microscopy imaging of point defects, associate this transition to the interplay between the defect-induced magnetism and the interlayer interactions in PtSe. Furthermore, we show that graphene can be effectively used to probe the magnetization of adjacent semiconducting PtSe. Our findings in an ultimately scaled monolayer system lay the foundation for atom-by-atom engineering of magnetism in otherwise non-magnetic 2D materials.
二维过渡金属二硫属化物中的原子尺度无序通常伴随着局部磁矩，这可以想象地将长程磁有序引入本征非磁性材料中。在这里，我们通过在横向和垂直测量配置下进行磁阻测量，证明了有缺陷的单层和双层半导体PtSe₂中长程磁有序的特征。随着材料从双层减薄到单层厚度，我们观察到铁磁到反铁磁的转变，这种行为与在典型二维磁体CrI₃中观察到的相反。我们的第一性原理计算，由点缺陷的像差校正透射电子显微镜成像支持，将这种转变与PtSe₂中缺陷诱导的磁性和层间相互作用之间的相互作用联系起来。此外，我们表明石墨烯可以有效地用于探测相邻半导体PtSe₂的磁化。我们在最终缩放的单层系统中的发现为在其他非磁性二维材料中逐原子工程化磁性奠定了基础。
