Spin Chains with Highly Quantum Character through Strong Covalency in Ca3CrN3

• Published in: Journal of the American Chemical Society Vol. 147; no. 4; pp. 3092 - 3101
• Main Authors: Kautzsch, Linus, Georgescu, Alexandru B., Yuan, Lin-Ding, Taddei, Keith M., Reilly, Aiden, Seshadri, Ram, Rondinelli, James M., Wilson, Stephen D.
• Format: Journal Article
• Language: English
• Published: American Chemical Society 29.01.2025
• ISSN: 0002-7863; 1520-5126; 1520-5126
• DOI: 10.1021/jacs.4c11629

The insulating transition metal nitride Ca3CrN3 consists of sheets of triangular [CrN3]6– units with C 2v symmetry that are connected via quasi-1D zigzag chains. Due to strong covalency between Cr and N, Cr3+ ions are unusually low-spin, and S = 1/2. Magnetic susceptibility measurements reveal dominant quasi-1D spin correlations with very large nearest-neighbor antiferromagnetic exchange J = 340 K and yet no sign of magnetic order down to T = 0.1 K. Density functional theory calculations are used to model the local electronic structure and the magnetic interactions, supporting the low-spin assignment of Cr3+ that is driven by strong π donation from the nitride ligands. The surprising failure of interchain exchange to drive long-range magnetic order is accounted for by the complex connectivity of the spin chain pairs that further frustrates order. Our combined results establish Ca3CrN3 as a nearly ideal manifestation of a quantum spin chain whose dynamics remain unquenched down to extraordinarily low temperatures despite strong near-neighbor exchange coupling.