Insulator-to-metal transition in BaCoS₂ via chlorine substitution

Our previous work highlighted the role of Jahn-Teller-associated displacements in the insulator-to-metal transition (IMT) in the BaCo_1-xNi_xS₂ system¹. Substitution of chlorine onto the sulfur site provides an alternate route to increasing the electron concentration past the IMT critical point. We leverage density functional theory to predict the charge, spin, and lattice behavior of BaCoS_2-xCl_x. In particular, we examine the influence of chlorine doping on the first-order Jahn-Teller effect arising from partial occupancy of nominally degenerate Co²⁺ d_xz and d_yz orbitals which is responsible for the insulating state in the undoped end member. Analysis of the resulting Jahn-Teller distortion and long-range orbital ordering allows us to compare the doping-induced metallization between the well-studied BaCo_1-xNi_xS₂ system and the novel BaCoS_2-xCl_x system.

¹ Schueller, E. C. et al., “Structural signatures of the insulator-to-metal transition in BaCo_1−xNi_xS₂,” Phys. Rev. Mater. 2020, 4 (10), 104401. 10.1103/PhysRevMaterials.4.104401