We present a detailed investigation of the physical properties of ${\mathrm{Ce}}_2\mathrm{Sb}$ and ${\mathrm{Ce}}_2\mathrm{Bi}$ single crystals, which undergo antiferromagnetic transitions at around 8.2 and 10 K, respectively. When magnetic fields are applied parallel to the $c$ axis, metamagnetic transitions are observed at low temperatures, corresponding to a magnetic field induced phase transition. It is found that the field induced transition changes from second order at higher temperatures, to first order at low temperatures, suggesting the existence of tricritical points (TCPs) in both compounds. Since replacing Bi with Sb suppresses the TCP to lower temperatures and corresponds to a positive chemical pressure, these results suggest that applying pressure to ${\mathrm{Ce}}_2\mathrm{Sb}$ may suppress the TCP to lower temperatures, potentially to zero temperature at a quantum tricritical point.

• Received 7 November 2018
• Revised 22 January 2019

DOI:https://doi.org/10.1103/PhysRevB.99.064419