When ferromagnetism goes 2D

CIC nanoGUNE Seminars

Efren Navarro-Moratalla, Universidad de Valencia, Valencia, Spain
nanoGUNE seminar room, Tolosa Hiribidea 76, Donostia - San Sebastian
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When ferromagnetism goes 2D The study of magnetism in one and two dimensions is a longstanding problem in condensed matter physics. Already half a century ago, Mermin and Wagner claimed that magnetic order in low dimensions is forbidden in an isotropic spin lattice.[1] A plethora of experiments have been performed thereafter to check the implications of this celebrated theorem in layered bulk crystalline materials as an approximation to a two-dimensional (2D) spin lattice. However, interlayer coupling in these systems is never negligible and an approach for the study of true 2D magnetism has been lacking to the date. With the avenue the 2D materials a genuine approach to low-dimensionality was unlocked. The realization of long-range magnetic order in a 2D material has been a tantalizing concept ever since the discovery of graphene given the high stakes of the incorporation of magnetism in van der Waals heterostructures for applications such as spintronics or topological superconductivity. In this talk I will present our recent discovery of the first true 2D ferromagnet made out of a single layer of a ferromagnetic insulator: chromium triiodide (CrI3).[2] Our experiments also showcase the dramatic layer dependence of the magnetic phase transitions and ground states in atomically-thin van der Waals crystals down to the monolayer and the intriguing metamagnetism emerging in bilayer CrI3. I will conclude by outlining the potential of this new class of 2D magnets for optoelectronic applications by the combination of magnetic hysteresis with helical luminescence in the monolayer limit.[3] [1] N. D. Mermin & H. Wagner, Phys. Rev. Lett. 17, 1133-1136 (1966) [2] B. Huang et al. Nature 117, 610 (2017) [3] K. L. Seyler et al. Nat. Phys. (2017) About Efren Navarro-Moratalla **Host** : L.E. Hueso