Bond-length-driven magnetic transition in quasi-one-dimensional CrSbX3 (X = S, Se)

초록

Using ab initio calculations, we investigate the magnetic ground states of quasi-one-dimensional insulating CrSb X3 ( X = S, Se) with infinite double-rutile chains. Within conventional band theory, without explicit Coulomb correlations ( U), we obtain band gaps in close agreement with experiment. Remarkably, we find that the magnetic order is highly sensitive to the Cr-Cr bond length dCr-Cr: increasing the bond length induces a transition from antiferromagnetic to ferromagnetic order at a critical distance dCr-Crc approximate to 3.53(+/- 0.05) & Aring;. Accordingly, CrSbS3 lies near the transition boundary, whereas CrSbSe3 is robustly ferromagnetic, in good agreement with experiment. Analysis of the exchange interactions reveals that the first-order phase transition is dominated by a sign reversal of the intrachain nearest-neighbor superexchange J1 mediated by chalcogen ions, while the intrachain direct exchange J2 remains ferromagnetic and changes only gradually. This behavior reflects an emergent Bethe-Slater-like behavior driven by competing exchange pathways in a quasi-1D transition-metal system, where the competition between J1 and J2 dictates the magnetic ground state. Besides, the electronic structures of the ground states of each compound are investigated.

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