2010/06/02 by Yogesh Singh, Singh, Yogesh, P. Gegenwart +1
Physics and Astronomy · #Advanced Condensed Matter Physics #FOS: Physical sciences #Materials Science (cond-mat.mtrl-sci) #Physics of Superconductivity and Magnetism #Quantum many-body systems #Strongly Correlated Electrons (cond-mat.str-el) #cond-mat.mtrl-sci #cond-mat.str-el
paper · pdf · doi:10.48550/arxiv.1006.0437
6 figures, 1 table. This preprint replaces arXiv:1003.1055 which has been withdrawn
arxiv created 2010/06/02 · openalex publication_date 2010/06/02 · arxiv updated 2010/06/03 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
We have synthesized single crystals of Na2IrO3 and studied their structure, transport, magnetic, and thermal properties using powder x-ray diffraction (PXRD), electrical resistivity, isothermal magnetization M versus magnetic field H, magnetic susceptibility χversus temperature T, and heat capacity C versus T measurements. Na2IrO3 crystallizes in the monoclinic C2/c (No. 15) type structure which is made up of Na and NaIr2O6 layers alternately stacked along the c axis. The χ(T) data show Curie-Weiss behavior at high T > 200K with an effective moment μeff = 1.82(1) μB indicating an effective spin Seff = 1/2 on the Ir4+ moments. A large Weiss temperature θ= - 116(3)K indicates substantial antiferromagnetic interactions between these Seff = 1/2, Ir4+ moments. Sharp anomalies in χ(T) and C(T) data indicate that Na2IrO3 undergoes a transition into a long-range antiferromagnetically ordered state below TN = 15 K. The magnetic entropy at TN is only about 20% of what is expected for Seff = 1/2 moment ordering. The reduced entropy and the small ratio TN/θ≈ 0.13 suggest geometrical magnetic frustration and/or low-dimensional magnetic interactions in Na2IrO3. In plane resistivity measurements show insulating behavior. This together with the local moment magnetism indicates that bulk Na2IrO3 is a Mott insulator.