A drastic change of the fermi surface at a critical pressure in CeRhIn5:: dHvA study under pressure

We carried out the de Haas-van Alphen (dHvA) experiment for an antiferromagnet CeRhIn5 at high pressures up to 3 GPa. The cross-sectional areas of the Fermi surfaces due to main dHvA branches alpha(i) and beta(2) at ambient pressure, which are well explained by two kinds of nearly cylindrical Fermi surfaces of a non-4f reference compound LaRhIn5, are unchanged up to about 2.3 GPa, while the corresponding cyclotron masses m(c)* increase steeply above a pressure P* = 1.6GPa where pressure-induced superconductivity Sets in : m(c)* = 5.5 m(0) at ambient pressure, 20 m(0) at 6 GPa and 60 m(0) at 2.2 GPa for branch 2, for example. Above 2.4 GPa, new dHvA branches appear, which are in good agreement with the corresponding dHvA branches of a 4f-itinerant heavy fermion superconductor CeCoIn5, indicating that the 4f electron of CeRhIn5 becomes itinerant and significantly contributes to the volume of the Fermi surface. The 4f-electron character is thus changed from localized to itinerant at a critical pressure P-c similar or equal to 2.35 GPa, where the superconducting transition temperature becomes a maximum.