Magnetic neutron diffraction in the novel triangular lattice antiferromagnet ErTa7O19

Rare-earth (RE) based geometrically frustrated magnets represent a promising avenue in the search of enigmatic quantum spin liquids (QSLs). Our previous study published in Nature Materials has identified a novel family of RE heptatantalates RETa7O19, where in the Nd case strong Ising anisotropy on the triangular lattice leads to a QSL state. As the nature of the RE has a strong influence on the magnetic anisotropy, which primarily determines the ground state on frustrated lattices, we hereby propose to study ErTa7O19 with the same crystal structure but twice as strong magnetic interactions and apparently XY magnetic anisotropy, according to our bulk magnetic measurements. Neither these nor specific-heat measurements show any signs of magnetic ordering down to 2 K. We propose a neutron diffraction study below 1 K to address the nature of the ground state in this compound.