Ground-state degeneracy and complex magnetism of geometrically frustrated Gd2Ir0.97Si2.97

We report a new triangular-lattice intermetallic compound Gd2Ir0.97Si2.97 was successfully synthesized as single phase by deliberately introducing vacancies. Theoretical analysis suggests that the ground state is competing with several low-energy spin configurations due to magnetic frustration on a nearly ideal triangular lattice. Despite a number of competing magnetic states, the compound exhibits long-range antiferromagnetic order at16K, a long-range ferrimagnetic transition at 6.5 K, and a reentrant cluster-glass transition below Tf ~ 3K. The complex magnetism in the compound could be correlated with competing antiferromagnetic and ferrimagnetic structures predicted theoretically.