Structural studies were performed on $R_3{\mathrm{Rh}}_4{\mathrm{Sn}}_{13}$ ($R$=La and Ce). X-ray diffraction measurements on single-crystalline samples of both Rh-based compounds, which were synthesized by the molten Sn-flux method, have revealed structural transformations below $T_{\mathrm{D}}\simeq$ 350 K. The low-temperature superstructures are characterized by the wave vector $\mathit{q}=(1/2,1/2,0)$. The space group in the low-temperature phases of both compounds is chiral cubic $I{2}_{1}3$, which is the same as that of $R_3{\mathrm{Co}}_4{\mathrm{Sn}}_{13}$ ($R$=La and Ce). Neutron diffraction measurement of ${\mathrm{Ce}}_3{\mathrm{Rh}}_4{\mathrm{Sn}}_{13}$ revealed no magnetic long-range order below the temperature of the specific-heat peaks at 1.2 and 1.8 K. The low-temperature magnetic state in the chiral phase is that of a paramagnetic semimetal, whereas the dynamical spin correlation of Ce is deduced from the specific-heat data, as found previously in ${\mathrm{Ce}}_3{\mathrm{Co}}_4{\mathrm{Sn}}_{13}$.

• Received 22 April 2018
• Revised 10 June 2018

DOI:https://doi.org/10.1103/PhysRevB.97.235138