title: Origin of long-range ferromagnetic ordering in metal-organic frameworks with antiferromagnetic dimeric-Cu(II) building units.
abstract: Even though metal-organic frameworks (MOFs) derived from antiferromagnetic dimeric-Cu(II) building units and nonmagnetic molecular linkers are known to exhibit unexpected ferromagnetic behavior, a comprehensive understanding of the underlying mechanism remains elusive. Using a combined theoretical and experimental approach, here we reveal the origin of the long-range ferromagnetic coupling in a series of MOFs, constructed from antiferromagnetic dimeric-Cu(II) building blocks. Our studies show that the strong localization of copper vacancy states favors spontaneous spin polarization and formation of local moment. These copper vacancy-induced moments are coupled via the itinerant electrons in the conjugated aromatic linkers to establish a long-range ferromagnetic ordering. The proposed mechanism is supported by direct experimental evidence of copper vacancies and the magnetic hysteresis (M-H) loops.
authors.affiliation: Department of Physics, 2 Science Drive 3, National University of Singapore, Singapore 117542, Singapore.
authors.forename: Lei
authors.initials: L
authors.lastname: Shen
authors.forename: Shuo-Wang
authors.initials: SW
authors.lastname: Yang
authors.forename: Shengchang
authors.initials: S
authors.lastname: Xiang
authors.forename: Tao
authors.initials: T
authors.lastname: Liu
authors.forename: Bangchuan
authors.initials: B
authors.lastname: Zhao
authors.forename: Man-Fai
authors.initials: MF
authors.lastname: Ng
authors.forename: Jörg
authors.initials: J
authors.lastname: Göettlicher
authors.forename: Jiabao
authors.initials: J
authors.lastname: Yi
authors.forename: Sean
authors.initials: S
authors.lastname: Li
authors.forename: Lan
authors.initials: L
authors.lastname: Wang
authors.forename: Jun
authors.initials: J
authors.lastname: Ding
authors.forename: Banglin
authors.initials: B
authors.lastname: Chen
authors.forename: Su-Huai
authors.initials: SH
authors.lastname: Wei
authors.forename: Yuan Ping
authors.initials: YP
authors.lastname: Feng
mesh_terms: D003300:Copper / Q000737:chemistry*; D019281:Dimerization; D008958:Models, Molecular; D009942:Organometallic Compounds / Q000737:chemistry*; D011789:Quantum Theory
chemical_list: D009942:Organometallic Compounds; D003300:Copper