The compounds LnAuAl4βGe2β (Ln= lanthanide) form in a structure
that features two-dimensional triangular lattices of Ln ions that are stacked
along the crystalline c axis. Together with crystal electric field effects,
magnetic anisotropy, and electron-mediated spin exchange interactions, this
sets the stage for the emergence of strongly correlated spin and electron
phenomena. Here we investigate SmAuAl4βGe2β, which exhibits weak
paramagnetism that strongly deviates from conventional Curie-Weiss behavior.
Complex antiferromagnetic ordering emerges at TN1β= 13.2 K and
TN2β= 7.4 K, where heat capacity measurements show that these
transitions are first and second order, respectively. These measurements also
reveal that the Sommerfeld coefficient is not enhanced compared to the
nonmagnetic analog YAuAl4βGe2β, consistent with the charge carrier
quasiparticles exhibiting typical Fermi liquid behavior. The
temperature-dependent electrical resistivity follows standard metallic
behavior, but linear magnetoresistance unexpectedly appears within the ordered
state. We compare these results to other LnAuAl4βGe2β materials, which
have already been established as localized f-electron magnets that are hosts
for interesting magnetic and electronic phases. From this, SmAuAl4βGe2β
emerges as a complex quantum spin metal, inviting further investigations into
its properties and the broader family of related materials.Comment: 9 pages, 6 figure