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Ab Initio study of magnetic interactions in the KCuF3 and K2CuF4 low-dimensional Systems
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The ab initio cluster model approach has been used to study the electronic structure and magnetic coupling of KCuF3 and K2CuF4 in their various ordered polytype crystal forms. Due to a cooperative Jahn-Teller distortion these systems exhibit strong anisotropies. In particular, the magnetic properties strongly differ from those of isomorphic compounds. Hence, KCuF3 is a quasi-one-dimensional (1D) nearest neighbor Heisenberg antiferromagnet whereas K2CuF4 is the only ferromagnet among the K2MF4 series of compounds (M=Mn, Fe, Co, Ni, and Cu) behaving all as quasi-2D nearest neighbor Heisenberg systems. Different ab initio techniques are used to explore the magnetic coupling in these systems. All methods, including unrestricted Hartree-Fock, are able to explain the magnetic ordering. However, quantitative agreement with experiment is reached only when using a state-of-the-art configuration interaction approach. Finally, an analysis of the dependence of the magnetic coupling constant with respect to distortion parameters is presented.
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MOREIRA, Ibério de Pinho Ribeiro and ILLAS I RIERA, Francesc. Ab Initio study of magnetic interactions in the KCuF3 and K2CuF4 low-dimensional Systems. Physical Review B. 1999. Vol. 60, num. 8, pags. 5179-5185. ISSN 0163-1829. [consulted: 8 of June of 2026]. Available at: https://hdl.handle.net/2445/10846