Anisotropic temperature-field phase diagram of single crystalline β -Li2IrO3 : Magnetization, specific heat, and 7Li NMR study
Abstract
Detailed magnetization, specific heat, and 7Li nuclear magnetic resonance (NMR) measurements on single crystals of the hyperhoneycomb Kitaev magnet β -Li2IrO3 are reported. At high temperatures, anisotropy of the magnetization is reflected by the different Curie-Weiss temperatures for different field directions, in agreement with the combination of a ferromagnetic Kitaev interaction (K ) and a negative off-diagonal anisotropy (Γ ) as two leading terms in the spin Hamiltonian. At low temperatures, magnetic fields applied along a or c have only a weak effect on the system and reduce the Néel temperature from 38 K at 0 T to about 35.5 K at 14 T, with no field-induced transitions observed up to 58 T on a powder sample. In contrast, the field applied along b causes a drastic reduction in the TN that vanishes around Hc=2.8 T , giving way to a crossover toward a quantum paramagnetic state. 7Li NMR measurements in this field-induced state reveal a gradual line broadening and a continuous evolution of the line shift with temperature, suggesting the development of local magnetic fields. The spin-lattice relaxation rate shows a peak around the crossover temperature 40 K and follows power-law behavior below this temperature.
- Publication:
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Physical Review Materials
- Pub Date:
- July 2019
- DOI:
- 10.1103/PhysRevMaterials.3.074408
- arXiv:
- arXiv:1906.09089
- Bibcode:
- 2019PhRvM...3g4408M
- Keywords:
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- Condensed Matter - Strongly Correlated Electrons;
- Condensed Matter - Materials Science
- E-Print:
- 10 pages, 9 figures