The de Haas–van Alphen effect and the Fermi surface in CePt₃Si and LaPt₃Si

Abstract

We have carried out a de Hass-van Alphen (dHvA) experiment for the recently discovered CePt 3 Si, which is the first heavy fermion superconductor without inversion symmetry in the tetragonal crystal structure, together with a dHvA experiment for a non-4f reference compound LaPt 3 Si. As for LaPt 3 Si, several dHvA branches were observed. Among them, the two main dHvA branches with the dHvA frequency (the cyclotron effective mass) of 1.10 × 10 8 Oe (1.4 m 0 ) and 8.41 × 10 7 Oe (1.5 m 0 ) were found to be well explained from the FLAPW energy band calculations, corresponding to bands 64-and 63-multiply-connected hole Fermi surfaces, respectively. On the other hand, the dHvA frequencies of 10 7 Oe in CePt 3 Si are small in magnitude, although the corresponding cyclotron masses of 10-20 m 0 are extremely large.The recently discovered superconductor CePt 3 Si is unique, possessing a few characteristics [1]. Superconductivity is realized in the long-range antiferromagnetic ordering. The Néel temperature is 2.2 K, while the superconducting transition temperature is 0.75 K. Both transitions were observed clearly in the specific heat measurement. The electronic specific heat coefficient γ is large, 300-400 mJ K −2 mol −1 . In the previous cerium-based heavy fermion superconductors including a prototype superconductor CeCu 2 Si 2 and a quasi-two dimensional superconductor CeCoIn 5 with a large γ value of 1000 mJ K −2 mol −1 , superconductivity occurs in the non-magnetic or antiferromagnetically spin-fluctuating state [2][3][4]. Another example is CeIn 3 under pressure [4][5][6]. At ambient pressure, the Néel temperature in CeIn 3 is T N = 10 K 4 Author to whom any correspondence should be addressed.

Magnetic phase diagram of CePt3B1−xSix

“…23 As result of the various pressure studies, most notably it is found that the antiferromagnetic state is already suppressed at a pressure of about 0.6 GPa, while superconductivity persists up to a pressure of 1.5 GPa. Thus, for noncentrosymmetric CePt 3 Si the appearance of superconductivity is closely linked to the suppression of magnetic order, although here quantum critical behavior has not been observed in the various physical properties.…”

Electron Correlation and Pairing States in Superconductors without Inversion Symmetry

“…Unfortunately, it is difficult to construct a reliable microscopic model for CePt 3 Si at the present moment, since experimental studies of microscopic electronic structure such as the de Haas-van Alphen effect have not yet succeeded in detecting the Fermi surface of heavy electrons in CePt 3 Si. 35 Very recently, Yanase and Sigrist have carried out microscopic calculations using the Fermi surface obtained by the LDA calculation, and found that the admixture of a p-wave state and an extended s-wave state is stabilized. 51 …”

“…[31][32][33][34] An intriguing feature of these systems is that according to LDA calculations and de Haas-van Alphen experiments, the SO splitting of the Fermi surfaces is much larger than the superconducting gap. 17,[35][36][37] For instance, in the case of CePt 3 Si, the magnitude of the SO splitting is nearly equal to 10 percent of the Fermi energy. 17,35 This large SO splitting indicates the important role of parity violation in these superconductors.…”

“…17,[35][36][37] For instance, in the case of CePt 3 Si, the magnitude of the SO splitting is nearly equal to 10 percent of the Fermi energy. 17,35 This large SO splitting indicates the important role of parity violation in these superconductors.…”

Magnetic ground-state properties of noncentrosymmetricCePt3B1−xSix

“…In this context, CePt 3 Si is the first heavy fermion superconductor with a lack of inversion symmetry of its crystallographic lattice 4 . This causes a spin-orbit splitting of the Fermi surface, which might generate chiral spin states 5 . A pure spin triplet pairing in such non-centrosymmetric system is excluded because of fundamental symmetry arguments 6 .…”