Exceedingly Small Moment Itinerant Ferromagnetism of Single Crystalline La${}_5$Co${}_2$Ge${}_3$

Abstract

Single crystals of monoclinic La${}_5$Co${}_2$Ge${}_3$ were grown using a self-flux method and were characterized by room-temperature powder X-ray diffraction, anisotropic temperature and field dependent magnetization, temperature dependent resistivity, specific heat, and muon spin rotation. La${}_5$Co${}_2$Ge${}_3$ has a Curie temperature ($T_{\mathrm{C}}$) of 3.8~K and clear signatures of ferromagnetism in magnetization and $\mu SR$ data, as well as a clear loss of spin disorder scattering in resistivity data and a sharp specific heat anomaly. The magnetism associated with La${}_5$Co${}_2$Ge${}_3$ is itinerant, has a change in the entropy at $T_{\mathrm{C}}$ of $\simeq$0.05 R ln2 per mol-Co, and has a low-field saturated moment of $\sim 0.1{\mu }_{\mathrm{B}}$/Co, making it a rare, itinerant, small moment, low $T_{\mathrm{C}}$ compound.