SKM 2023 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 21: Correlated Electrons: Electronic Structure Calculations

TT 21.8: Vortrag

Dienstag, 28. März 2023, 11:15–11:30, HSZ 201

Quantum chemical study on cobalt(II) in honeycomb lattices based on multi-configurational approaches — •Thorben Petersen and Liviu Hozoi — Leibniz IFW Dresden, 01069 Dresden, Germany

Quantum Spin Liquids (QSLs) are fascinating materials that display quantum entanglement and host unconventional fractionated excitations. While QSL behavior was found in Cu(II) 3d⁹ cuprates, 4d⁵ RuCl₃, 5d⁵ iridates and triangular-lattice 4f¹³ oxides, we here explore 3d⁷ Co(II) compounds such as Na₂Co₂TeO₆, which form spin-orbit-entangled J_eff=1/2 pseudo-spin moments at Co(II) sites that potentially realize Kitaev-magnetism. In this study, we apply multi-configurational quantum-chemistry methods like CASSCF and beyond to model the t_2g⁵ e_g² magnetic sites in these honeycomb oxides by carefully designing an embedded cluster model to represent the extended bulk lattice. With this, we quantify the extent of the 3d-site multiplet structure and spin-orbit coupling associated with the ⁴T_2g ground state term. Moreover, our model will be validated against experimental magnetization data and first impressions on the 3d⁷-3d⁷ intersite couplings will be given.