Critical spin fluctuations in the heavy-fermion antiferromagnets Ce2Bi and Ce2Sb

The compounds Ce2Bi and Ce2Sb represent rare examples of the heavy fermion materials that exhibit the coexistence of an antiferromagnetic magnetic order and a tricritical point (TCP) in their temperature-magnetic field phase diagram. The magnetic and resistivity measurements of Ce2Sb and Ce2Bi showed that both materials exhibit AFM ground states. Moreover, the measurements revealed metamagnetic transitions which show a crossover from a second-order transition at elevated temperatures, to first order behavior, which indicates the presence of TCPs in the phase diagrams of these materials. We intend to study the magnetic fluctuations in these two materials in the vicinity of the tricritical point by means of low-energy TOF spectroscopy. We will demonstrate that Ce2Sb hosts stronger spin fluctuations than Ce2Bi, as it has a larger unit cell volume and is closer to a quantum TCP.