Magnetic Properties of Heavy Fermion Compound Ce5Si4 with Chiral Structure

The low-temperature magnetic properties of Ce₅Si₄ with a chiral structure have been studied by electrical resistivity, heat capacity, and magnetization measurements using single-crystalline samples. It is found that Ce₅Si₄ is an antiferromagnet with moderately correlated electronic states. The resistivity decreases strongly under magnetic fields, indicating scaling behavior based on the Coqblin-Schrieffer model. The obtained characteristic energy scale of the Kondo effect is clearly anisotropic for the magnetic field H ∥ a-axis and H ∥ c-axis in the tetragonal structure, possibly related to the anisotropic antiferromagnetic phase. Furthermore, in the antiferromagnetic phase, a shoulderlike crossover anomaly is observed in C/T. A possible scenario is that non-ordered Ce atoms exist even below T_N in this chiral system.