Most of the Eu compounds are in the divalent (Eu2+) electronic state and order magnetically. On the other hand, the Eu-trivalent (Eu3+) compounds exist but are small in number. An energy difference between the Eu2+ and Eu3+ states is, however, not extremely large. Therefore, the valence transition occurs in some Eu compounds. We present the characteristic properties of the Eu compounds from several viewpoints: a canting magnetisation in the Eu2+-antiferromagnets, the Fermi surface property in the Eu3+-compounds of EuPd3 and EuCo2 Si2, the heavy fermion state in EuNi2 P2, the temperature-induced valence transition in EuPd2 Si2, the pressure-induced valence transition in EuRh2 Si2 and EuRu2 P2, and the heavy fermion state approaching to the quantum critical point with increasing pressure in Eu2 Ni3 Ge5.
All Science Journal Classification (ASJC) codes
- Condensed Matter Physics