  In high-energy heavy-ion collisions, partonic collectivity is evidenced by
the constituent quark number scaling of elliptic flow anisotropy for identified
hadrons. A breaking of this scaling and dominance of baryonic interactions is
found for identified hadron collective flow measurements in $\sqrt{s_{\rm NN}}$
= 3 GeV Au+Au collisions. In this paper, we report measurements of the first-
and second-order azimuthal anisotropic parameters, $v_1$ and $v_2$, of light
nuclei ($d$, $t$, $^{3}$He, $^{4}$He) produced in $\sqrt{s_{\rm NN}}$ = 3 GeV
Au+Au collisions at the STAR experiment. An atomic mass number scaling is found
in the measured $v_1$ slopes of light nuclei at mid-rapidity. For the measured
$v_2$ magnitude, a strong rapidity dependence is observed. Unlike $v_2$ at
higher collision energies, the $v_2$ values at mid-rapidity for all light
nuclei are negative and no scaling is observed with the atomic mass number.
Calculations by the Jet AA Microscopic Transport Model (JAM), with baryonic
mean-field plus nucleon coalescence, are in good agreement with our
observations, implying baryonic interactions dominate the collective dynamics
in 3 GeV Au+Au collisions at RHIC.
