Fermi surface instability in (formula presented) under pressure

That the (formula presented) electrons in the rare-earth antiferromagnetic compound (formula presented) should be considered as localized electrons at cerium sites has been confirmed by comparing a de Haas–van Alphen experiment to the result of energy band calculations for (formula presented) When pressure p is applied to the compound, the Néel temperature (formula presented) decreases and finally becomes zero at (formula presented)–1.1 GPa. The topology of the Fermi surface is found to be almost unchanged up to 1.0 GPa, but the cyclotron effective mass increases with increasing pressure. Above 1.1 GPa, the topology of the Fermi surface changes abruptly. A new Fermi surface is explained by the (formula presented)-itinerant-band model. The corresponding cyclotron mass is large, being about (formula presented).