De Haas–Van Alphen experiments under extreme conditions of low temperature, high field and high pressure, for high-quality cerium and uranium compounds

Abstract

When pressure is applied to cerium and uranium compounds, the magnetic ordering temperature is suppressed and becomes zero at a critical pressure P c. Around P c, non-Fermi liquid and/or superconductivity are observed. We clarified a change of the electronic state via a de Haas–van Alphen (dHvA) experiment when pressure crosses P c. The dHvA experiment under pressure was done for the antiferromagnets CeRh 2Si 2 and CeRhIn 5, and for a ferromagnet UGe 2. We found an abrupt change of the Fermi surface for CeRh 2Si 2 and UGe2 when crossing P c, indicating a first-order like phase transition. For CeRhIn 5, the topology of the Fermi surface was unchanged, but the cyclotron mass increased steeply above 1.6 Gpa, where superconductivity sets in.