Magnetic ground state of geometrically frustrated triangular lattice TbTa7O19 using muon spin rotation and relaxation investigations

Investigation of geometrically frustrated antiferromagnets is an active area of research in condensed matter physics in search for novel quantum magnetism. Competing exchange interactions in these materials can lead to highly degenerate ground states and unconventional quantum phenomena, such as quantum spin liquid. Rare earth based triangular antiferromagnets of general chemical formula RTa7O19 (R = magnetic trivalent rare earth) have attracted considerable interest in recent times in the field of frustrated magnetism. In such a background, we have experimentally characterized the R = Tb member of this series, TbTa7O19, through combined structural, chemical, magnetic, thermodynamic, and neutron scattering (elastic and inelastic) investigations. Interestingly, the heat capacity and ac magnetic susceptibility measurements (down to 50 mK) exhibit a clear phase transition at about 0.75 K in one sample-batch (sample-1), indicating magnetic ordering of the Tb moments, while, the other sample-batch (sample-2) doesn’t magnetically order down to 50 mK. However, neutron diffraction study on WISH (RB2410700) down to 50mK did not observe any magnetic Bragg peaks. Therefore, in order to get deeper insights into the true magnetic ground states of these two distinct batches of TbTa7O19, we plan to perform microscopic local magnetic probe muon-spin-relaxation experiments down to sub-Kelvin temperatures (~50 mK) on HiFi spectrometer of ISIS muon facility.