Filling in the Holes: Structural and Magnetic Properties of the Chemical Pressure Stabilized LnMnxGa3 (Ln = Ho–Tm; x < 0.15)

Single crystals of LnMnxGa3 (Ln = Ho–Tm; x 3 structure type where Mn partially occupies the Ga6 octahedral holes. Introduction of the Mn guest atoms allows for modulation of the structures and magnetic properties of their hosts: While TmGa3 orders antiferromagnetically at ∼4.2 K, TmMnxGa3 (x = 0.05, 0.10) remains paramagnetic down to 1.8 K. Ho and Er analogs order antiferromagnetically, with effective moments and Néel temperatures, respectively, decreasing and increasing as a function of Mn concentration. DFT–chemical pressure analysis elucidates the trends in the stability of LnGa3 AuCu3-type phases and their stuffed derivatives. Guest atom insertion supports expansion of the filled octahedra, allowing the relief of negative chemical pressures in the surrounding Ga–Ga contacts.