2017/07/13 by Xing Ming, Carmine Autieri, Kunihiko Yamauchi +1 · 18 citations
Chemistry · Materials Science · Physics and Astronomy · #Advanced Condensed Matter Physics #Antiferromagnetism #Chemistry #Computer science #Condensed matter physics #Crystallography #Electronic structure #Frustration #Magnetic and transport properties of perovskites and related materials #Magnetic moment #Physics #Physics of Superconductivity and Magnetism #Planar #cond-mat.str-el
paper · pdf · doi:10.1103/physrevb.96.205158
published in Physical review. B./Physical review. B 96(20) (American Physical Society) · 23 pages, 7 figures
arxiv created 2017/07/13 · openalex created_date 2017/07/21 · openalex publication_date 2017/11/30 · arxiv updated 2017/12/13 · openalex updated_date 2026/08/05
Iridates supply fertile ground for unconventional phenomena and exotic electronic phases. With respect to well-studied octahedrally coordinated iridates, we focus our attention on a rather unexplored iridate, Na4IrO4, showing an unusual square planar coordination. The latter is key to rationalizing the electronic structure and magnetic property of Na4IrO4, which is here explored by first-principles density functional theory calculations and Monte Carlo simulations. Due to the uncommon square planar crystal field, Ir 5d states adopt an intermediate-spin state with double occupation of the d_z2 orbital, leading to a sizable local spin moment, at variance with many other iridates. The square planar crystal-field splitting is also crucial in opening a robust insulating gap in Na4IrO4, irrespective of the specific magnetic ordering or treatment of electronic correlations. Spin-orbit coupling plays a minor role in shaping the electronic structure, but leads to strong magnetocrystalline anisotropy. The easy axis perpendicular to the IrO4 plaquette, well explained using perturbation theory, is again closely related to the square planar coordination. Finally, the large single-ion anisotropy suppresses the spin frustration and stabilizes a collinear antiferromagnetic long-range magnetic ordering, as confirmed by Monte Carlo simulations predicting a quite low N'eel temperature, expected from almost isolated IrO4 square planar units that act as crystalline building blocks.