The Superexchange mechanism in crystalline compounds. The case of KMF3(M=Mn, Fe, Co, Ni) perovskites. - Université de Lorraine Access content directly
Journal Articles Journal of Physics: Condensed Matter Year : 2021

The Superexchange mechanism in crystalline compounds. The case of KMF3(M=Mn, Fe, Co, Ni) perovskites.

Abstract

Abstract The ferromagnetic and antiferromagnetic wavefunctions of four KMF 3 (M= Mn, Fe, Co and Ni) perovskites have been obtained quantum-mechanically with the CRYSTAL code, by using the Hartree-Fock (HF) Hamiltonian and three flavours of DFT (PBE, B3LYP and PBE0) and an all-electron Gaussian type basis set. In the Fe and Co cases, with d6and d7occupation, the Jahn-Teller distortion of the cubic cell is as large as 0.12 Å. Various features of the superexchange interaction energies (SIE), namely additivity, dependence on the M-M distance, on the MFM̂ angle, and on the adopted functional, are explored. The contribution to SIE by the Coulomb, exchange and kinetic energy terms is analyzed. It is shown that, when using density functionals, SIE clearly correlates with the amount of exact (Hartree-Fock) exchange in the functional. The effect of SIE on the equilibrium geometry and volume of the unit cell is discussed, and it is shown that the key quantity is the spin polarization of the (closed shell) F ions along the M-F-M path. The effect of this magnetic pressure is evaluated quantitatively for the first time.
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Dates and versions

hal-03424377 , version 1 (10-11-2021)

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Fabien Pascale, Philippe D’arco, Valentina Lacivita, Roberto Dovesi. The Superexchange mechanism in crystalline compounds. The case of KMF3(M=Mn, Fe, Co, Ni) perovskites.. Journal of Physics: Condensed Matter, 2021, 32, pp.074002. ⟨10.1088/1361-648X/ac36fe⟩. ⟨hal-03424377⟩
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