Elliptic flow of identified hadrons in Au+Au collisions at<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msqrt><mml:msub><mml:mi>s</mml:mi><mml:mi mathvariant="italic">NN</mml:mi></mml:msub></mml:msqrt><mml:mo>=</mml:mo><mml:mn>7.7</mml:mn></mml:mrow></mml:math>–62.4 GeV

Measurements of the elliptic flow, ${v}_{2}$, of identified hadrons (${\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}}$, ${K}^{\ifmmode\pm\else\textpm\fi{}}$, ${K}_{s}^{0}$, $p$, $\overline{p}$, $\ensuremath{\phi}$, $\ensuremath{\Lambda}$, $\overline{\ensuremath{\Lambda}}$, ${\ensuremath{\Xi}}^{\ensuremath{-}}$, ${\overline{\ensuremath{\Xi}}}^{+}$, ${\ensuremath{\Omega}}^{\ensuremath{-}}$, ${\overline{\ensuremath{\Omega}}}^{+}$) in $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{{s}_{\mathit{NN}}}=7.7$, 11.5, 19.6, 27, 39, and 62.4 GeV are presented. The measurements were done at midrapidity using the time-projection chamber and the time-of-flight detectors of the Solenoidal Tracker at RHIC experiment during the beam-energy scan program at Relativistic Heavy Ion Collider. A significant difference in the ${v}_{2}$ values for particles and the corresponding antiparticles was observed at all transverse momenta for the first time. The difference increases with decreasing center-of-mass energy, $\sqrt{{s}_{\mathit{NN}}}$ (or increasing baryon chemical potential, ${\ensuremath{\mu}}_{B}$), and is larger for the baryons as compared to the mesons. This implies that particles and antiparticles are no longer consistent with the universal number-of-constituent quark (NCQ) scaling of ${v}_{2}$ that was observed at $\sqrt{{s}_{\mathit{NN}}}=200$ GeV. However, for the selected group of particles (${\ensuremath{\pi}}^{+}$, ${K}^{+}$, ${K}_{s}^{0}$, $p$, $\ensuremath{\Lambda}$, ${\ensuremath{\Xi}}^{\ensuremath{-}}$, ${\ensuremath{\Omega}}^{\ensuremath{-}}$) NCQ scaling at $({m}_{T}\ensuremath{-}{m}_{0})/{n}_{q}&gt;0.4$ GeV/${c}^{2}$ is not violated within $\ifmmode\pm\else\textpm\fi{}10%$. The ${v}_{2}$ values for $\ensuremath{\phi}$ mesons at 7.7 and 11.5 GeV are approximately two standard deviations from the trend defined by the other hadrons at the highest measured ${p}_{T}$ values.