Competing magnetic states in silicene and germanene 2D ferromagnets
silicene, germanene, two-dimensional (2D) ferromagnetism, X-ray magnetic circular dichroism (XMCD), monolayer
Two-dimensional (2D) magnets have recently developed into a class of stoichiometric materials with prospective applications in ultra-compact spintronics and quantum computing. Their functionality is particularly rich when different magnetic orders are competing in the same material. Metalloxenes REX2 (RE = Eu, Gd; X = Si, Ge), silicene or germanene—heavy counterparts of graphene—coupled with a layer of rare-earth metals, evolve from three-dimensional (3D) antiferromagnets in multilayer structures to 2D ferromagnets in a few monolayers. This evolution, however, does not lead to fully saturated 2D ferromagnetism, pointing at a possibility of coexisting/ competing magnetic states. Here, REX2 magnetism is explored with element-selective X-ray magnetic circular dichroism (XMCD). The measurements are carried out for GdSi2, EuSi2, GdGe2, and EuGe2 of different thicknesses down to 1 monolayer employing K absorption edges of Si and Ge as well as M and L edges of the rare-earths. They access the magnetic state in REX2 and determine the seat of magnetism, orbital, and spin contributions to the magnetic moment. High-field measurements probe remnants of the bulk antiferromagnetism in 2D REX2. The results provide a new platform for studies of complex magnetic structures in 2D materials.
Tsinghua University Press
Dmitry V. Averyanov, Ivan S. Sokolov, Mikhail S. Platunov, Fabrice Wilhelm, Andrei Rogalev, Pierluigi Gargiani, Manuel Valvidares, Nicolas Jaouen, Oleg E. Parfenov, Alexander N. Taldenkov, Igor A. Karateev, Andrey M. Tokmachev, Vyacheslav G. Storchak. Competing magnetic states in silicene and germanene 2D ferromagnets. Nano Research 2020, 13(12): 3396-3402.