Berlin 2024 – scientific programme
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MA: Fachverband Magnetismus
MA 4: Magnetic Heusler Compounds and Complex Magnetic Oxides
MA 4.5: Talk
Monday, March 18, 2024, 10:30–10:45, EB 107
Quasi two dimensional antiferromagnetism in square planar iridate Cs2Na2IrO4 — •Roumita Roy1 and Sudipta Kanungo2 — 1Indian Institute of Technology Goa, India — 2Indian Institute of Technology Goa, India
The study of iridates has gained major attention in recent times, as it is a promising candidate to study the the delicate interplay amongst competing energy scales. However the constant focus has been on Ir in the octahedral or tetrahedral environment. In this work we report the rare occurrence of square planar iridate Cs2Na2IrO4. The structure consists of isolated IrO4 planes, orthogonally oriented in consecutive layers. Our work involves the detailed study of electronic and magnetic properties of Cs2Na2IrO4, from first principles calculations. Microscopic magnetic exchange interactions and Wannier function analysis reveals the quasi two dimensional canted AFM ground state, despite the absence of long range structural connectivity which originates because of very weak spin-phonon coupling. Further, the origin of orthogonally placed IrO4 moieties can be understood from the phonon modes analysis. Belonging to the 5d series, Ir is known to be substantially impacted by SOC. However due to the half-filled situation, the orbital magnetic moment is quenched in this case. Nevertheless we still obtain a large magneto-crystalline anisotropy which could be explained from the second-order perturbation theory. As a guiding tool to experimentalists, we also report preliminary work on muon active sites which is crucial in obtaining the magnetic structure of the system for future studies.
Keywords: Iridates; Spin orbit coupling; Magneto-crystalline anisotropy; Spin-phonon coupling; Muon site calculation