Exceedingly Small Moment Itinerant Ferromagnetism of Single Crystalline La5Co2Ge3

Single crystals of monoclinic ${\mathrm{La}}_{5}{\mathrm{Co}}_{2}{\mathrm{Ge}}_{3}$ 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. ${\mathrm{La}}_{5}{\mathrm{Co}}_{2}{\mathrm{Ge}}_{3}$ has a Curie temperature (${T}_{\mathrm{C}}$) of 3.8 K and clear signatures of ferromagnetism in magnetization and $\ensuremath{\mu}\mathrm{SR}$ data, as well as a clear loss of spin disorder scattering in resistivity data and a sharp specific heat anomaly. The magnetism associated with ${\mathrm{La}}_{5}{\mathrm{Co}}_{2}{\mathrm{Ge}}_{3}$ is itinerant has a change in the entropy at ${T}_{\mathrm{C}}$ of $\ensuremath{\simeq}0.05Rln2$ per mol Co and has a low-field saturated moment of $\ensuremath{\sim}0.1\phantom{\rule{0.16em}{0ex}}{\ensuremath{\mu}}_{\mathrm{B}}/\mathrm{Co}$, making it a rare, itinerant, small moment, low-${T}_{\mathrm{C}}$ compound.