EuPd2Si2, EuT2P2 (T=Ru,Fe,Co), YbInCu4 contain rare elements with a nearly filled or half-filled 4f shell. The lanthanide shows a strong change of its valence state upon changing temperature or pressure.
Semiconducting materials like EuCd2P2 or EuZn2P2 came recently in the focus of research as they exihibit unusual transport properties (CMR effect).
In YbNi4P2, YbNi4(P1-xAsx)2, YbRh2Si2, CeTPO (T=Ru,Fe) the conduction electrons interact strongly with each other and with the local magnetic moments of the rare-earth ions. The systems allow for studying quantum critical points.
The compounds LnT2Si2 (Ln= lanthanide, T=Rh,Ir) are of particular interest. Besides a large variety of different arrangements of their magnetic moments in the antiferromagnetic bulk or the occurrence of the Kondo effect, many of these materials host surface states which are tunable with temperature and make them interesting model systems for spintronic applications.
Systems like LnCo2P2, GdCo2Si2, LnMn2X2 (Ln=lanthanide, X=Si,Ge) are characterized by high magnetic ordering temperatures occurring due to the ordering of the transition metals itinerant electrons. Some show additional local moment magnetism of the 4f local moments.
MnBi2Te4, GdRu2Si2
EuO, EuS serve as Heisenberg model systems and can be grown at temperatures higher than 2300°C.
For instance F-doped LaOFeAs shows unconventional superconductivity with Tc above 50K.
The compounds YbRh2Si2, CeIrIn5 show unconventional superconductivity at very low temperatures.