Ironing out the transition metal contribution to the magnetism of the n = 3 members of the homologous series Prn+1MnGe3n+1 (M = Fe, Co): Pr4Fe3Ge10 vs. Pr4Co3Ge10

Abstract

The Lnn+1MnX3n+1 (Ln = lanthanide, M = transition metal, and X = tetrel) homologous series provides a platform to study collective phenomena in quantum materials. In this work, we compare the crystal growth, structure, and magnetic properties of the n = 3 members of the Prn+1MnGe3n+1 (M = Fe, Co) analogues, Pr4Fe3Ge10 (a = 4.3207 (10) Å, b = 35.523 (8) Å, c = 4.2982 (15) Å, and V = 659.7 (3) Å3) and Pr4Co3Ge10 (a = 4.3091 (12) Å, b = 35.750 (9) Å, c = 4.2807 (11) Å, and V = 659.4 (3) Å3). We determined that the ideal flux growth conditions for each compound are highly dependent on the concentration of Sn flux and quench temperature. Pr4Fe3Ge10 orders ferromagnetically at 10 K along the c-direction while Pr4Co3Ge10 orders antiferromagnetically at 16 K along the b-direction. For both compounds, we observed a magnetic moment higher than that expected for only Pr3+ ions (3.58 µB/Pr), implying that the transition metal ions contribute to magnetic ordering (3.91, 3.48, and 3.69 µB/Pr for Pr4Fe3Ge10, and 3.76, 4.04, and 3.83 µB/Pr for Pr4Co3Ge10 measured along the a-, b-, and c-directions, respectively). Moreover, the zero-field Mössbauer spectrum obtained at 4.2 K for Pr4Fe3Ge10 demonstrates that the iron sites participate in magnetic ordering.