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.