Berlin 2018 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 47: Frustrated Magnets - Iridates and Fe-based Materials

TT 47.3: Vortrag

Mittwoch, 14. März 2018, 10:00–10:15, H 0104

NMR studies on the single crystalline Na₂IrO₃: A model system to realize Kitaev interaction — •R. Sarkar¹, Z. Mei², A. Ruiz^3,4, H.-H. Klauss¹, J. G. Analytis^3,4, and N. J. Curro² — ¹Institute of Solid State and Materials Physics, Technical University of Dresden, 01062 Dresden, Germany — ²Department of Physics, University of California, Davis, California 95616, USA — ³Department of Physics, University of California, Berkeley, California 94720, USA — ⁴Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA

We present results of ²³Na nuclear magnetic resonance (NMR) measurements on single crystalline Na₂IrO₃, a possible candidate to realize Kitaev spin model on the honeycomb lattice. The NMR shifts (²³K(%)), that is the measure of local susceptibility, have been studied in two crystallographic orientations. The NMR shifts reflect strong anisotropic behavior similar to the bulk susceptibility. However, below a temperature T^* ∼ 50 K, the shift deviates from the bulk susceptibility. This anomalous behavior may be related to the exchange anisotropic bond interaction connected to the magnetic frustration. In contrast to the Knight shift, the spin-lattice relaxation rate ²³(1/T₁) is isotropic in the paramagnetic state and exhibits a strong peak at T_N. Deep in the ordered state, ²³(T₁T)⁻¹ approaches a constant value as a function of temperature, suggesting the presence of significant dynamics and/or the band of excitations associated with the close proximity of quantum spin liquid ground state of Na₂IrO₃.