Contribution of J-multiplet levels to the physical properties of EuPd₃ with the trivalent electronic state

EuPd₃ is one of the few Eu intermetallic compounds with the trivalent electronic state of the Eu ion. We succeeded in growing single crystals of EuPd₃ by the Bridgeman method, and studied the electronic, thermal, and magnetic properties by measuring the electrical resistivity, specific heat, thermal expansion, magnetic susceptibility, and magnetization. The observed temperature dependences of the magnetic susceptibility in the temperature range between 2 and 800K and of specific heat up to 150K are analyzed by considering the contribution of the J-multiplet levels ⁷F_J with J = 0-6. Since the ground-state J-multiplet ⁷F₀ is a singlet for the trivalent Eu ion, the magnetic susceptibility is due mainly to the mixing of the excited J-multiplet levels to the ground state by applying a magnetic field. The observed magnetic susceptibility can be explained by considering the mixing of the J-multiplet levels with J = 0-4. In addition, the specific heat data are well analyzed using the same J-multiplet levels with J = 0-2, showing a large specific heat contribution due to the J-multiplet levels even below room temperature. The excited levels with larger J values are located at much higher energies than the present experimental temperature range and irrelevant to the analyses.