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

Abstract

Single crystals of LnMnxGa3 (Ln = Ho–Tm; x < 0.15) were grown from a Ga self-flux. These compounds crystallize in a variant of the AuCu3 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 Neel 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.