Change of the electronic states in [formula omitted], [formula omitted] and [formula omitted] Si tuned by pressure

Abstract

We have studied a change of the electronic states in antiferromagnets CeIn 3, CeRhIn 5 and CePt 3Si via the de Haas–van Alphen experiments. The critical pressure P c , where the Néel temperature becomes zero, is P c ≃ 2.5 GPa in CeIn 3 with the cubic crystal structure, in which the narrow pressure region superconductivity appears below a superconducting transition temperature T sc = 0.2 K. In the pressure region P > P c , we detected a main Fermi surface with the cyclotron mass m c ∗ = 53 m 0 , which most likely corresponds to a nearly spherical Fermi surface in the paramagnetic state, namely a 4f-itinerant Fermi surface. The Fermi surface in the antiferromagnet CeRhIn 5 with the tetragonal crystal structure is similar to that of LaRhIn 5, consisting of two kinds of nearly cylindrical Fermi surfaces. We observed a drastic change of the Fermi surface from 4f-localized (LaRhIn 5) to 4f-itinerant (CeCoIn 5) Fermi surfaces at P c ≃ 2.4 GPa. The cyclotron mass increases intensively above 1.6 GPa where superconductivity sets in. CePt 3Si with the tetragonal crystal structure without inversion symmetry is highly different from CeIn 3 and CeRhIn 5 in magnetism and superconductivity. It orders antiferromagnetically below T N = 2.3 K and becomes superconductive below T sc = 0.6 K at ambient pressure. With increasing pressure, the cyclotron mass is found to be reduced, together with a steep decrease of T N and T sc , where P c is most likely about 1.5 GPa in CePt 3Si. The heavy fermion state of CePt 3Si is realized at ambient pressure.