Optimized flux single-crystal growth of the quantum spin liquid candidate NdTa$_7$O$_{19}$ and other rare-earth heptatantalates, ErTa$_7$O$_{19}$ and GdTa$_7$O$_{19}$Šibav, Lia (Avtor) Lozinšek, Matic (Avtor) Jagličić, Zvonko (Avtor) Arh, Tina (Avtor) Khuntia, Panchanana (Avtor) Zorko, Andrej (Avtor) Dragomir, Mirela (Avtor) quantum spin liquidsingle-crystal growthmagnetic propertiesfluxrare-earth tantalatescrystal structurecrystallizationcrystalsSingle crystals are essential for characterizing a wide range of magnetic states, including exotic ones such as quantum spin liquids. This study reports a flux method for growing single crystals of NdTa$_7$O$_{19}$, the first quantum spin liquid candidate on a triangular spin-lattice with dominant Ising-like spin correlations. Purple NdTa$_7$O$_{19}$ single crystals with hexagonal morphology were successfully grown by using a K$_2$Mo$_3$O$_{10}$−B$_2$O$_3$ flux. With lateral sizes up to 3.5 mm and a thickness up to 2 mm, these are the largest dimensions reported to date. The chemical composition was confirmed by powder and single-crystal X-ray diffraction along with scanning electron microscopy with energy dispersive X-ray spectroscopy. Aiming for an accurate determination of the magnetic anisotropy and its effect on the magnetic properties, NdTa$_7$O$_{19}$ crystals were additionally analyzed by magnetic susceptibility, revealing a substantial anisotropy without long-range magnetic ordering down to 2 K. Single crystals of two novel rare-earth heptatantalates, ErTa$_7$O$_{19}$ and GdTa$_7$O$_{19}$, were also grown, and their magnetic properties investigated. The magnetic anisotropy of ErTa$_7$O$_{19}$ closely resembles that of isostructural NdTa$_7$O$_{19}$, indicating the possibility of a similar exotic magnetic ground state. In contrast, GdTa$_7$O$_{19}$ shows paramagnetic behavior, consistent with previous results obtained for polycrystalline samples.20252025-12-03 13:50:57Članek v reviji176548UDK: 546ISSN pri članku: 1528-7505DOI: 10.1021/acs.cgd.5c00624COBISS_ID: 238455811sl