Origin of the insulating state in the honeycomb iridate Cu2IrO3

Journal article

Through a combination of crystal symmetry analysis and density functional theory calculations we unveil a possible microscopic origin of the unexpected insulating behavior reported in the honeycomb Kitaev material Cu₂⁢IrO₃. Our study suggests that this material hosts an instability towards charge ordering of the Ir ions, with alternating magnetic Ir⁴⁺ and nonmagnetic Ir³⁺ ions arranged on the honeycomb lattice. In this case, the next-nearest-neighbor interactions that couple magnetic Ir⁴⁺ ions form an enlarged triangular lattice, instead of the expected honeycomb lattice. The magnetic Cu²⁺ ions located at the center of the iridium honeycomb voids also form a triangular lattice, and additionally contribute to the magnetization of the system. Together, the interpenetrated Ir⁴⁺ and Cu²⁺ triangular lattices present a novel type of honeycomb Kitaev lattice composed of two types of magnetic ion.

Authors: Li, Y; Johnson, RD; Singh, Y; Coldea, R; Valentí, R

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: American Physical Society
• Journal: Physical Review B
• Volume: 111
• Issue: 24
• Article number: 245122
• Publication date: 2025-06-09
• Acceptance date: 2025-05-19
• DOI: 10.1103/physrevb.111.245122
• EISSN: 2469-9969
• ISSN: 2469-9950
• Language: English