Quasi-two-dimensional Fermi surfaces and the de Haas-van Alphen oscillation in both the normal and superconducting mixed states of CeCoIn₅

Abstract

We observed de Haas-van Alphen (dHvA) oscillation in both the normal and superconducting mixed states of a heavy-fermion superconductor CeCoIn5. The Fermi surfaces are found to consist of nearly cylindrical Fermi surfaces and small ellipsoidal ones, reflecting the unique tetragonal crystal structure. The detected cyclotron masses of 5-87 m0 for these Fermi surfaces are extremely large, and correspond to a large electronic specific heat coefficient of about 1000 mJ K-2 mol-1. The cyclotron masses are also found to be field dependent in both the normal and mixed states.

Fermi-surface evolution in Yb-substituted CeCoIn5

“…The β 1 and β 2 frequencies can be assigned to orbits of a complicated multiconnected Fermi surface with strongly renormalized heavy masses. 34 As mentioned, the sample with x = 0.2 reveals dHvA frequencies composed of both kinds of Fermi-surface topologies.…”

“…A likely candidate might be the band that gives rise to the complicated multiconnected Fermi surface resulting in the β orbits in CeCoIn 5 . 34 For both of these orbits, β 1 and β 2 , we find effective masses of about 53m e at 13 T and 010 = 7 • . For x = 0.1, we estimate an effective mass of about 26m e for the β 2 orbit [ Fig.…”

“…34,35 This reflects that Kondo physics is relevant and that possibly quantum critical fluctuations also play a role.…”

“…For the latter, the strongest spectral peaks are labeled α 1 to α 3 according to the assignment of earlier studies to which we find very good agreement both in the dHvA frequencies as well as in the effective masses (discussed below). 34,35 In our measurements up to 20 T, we could just barely resolve dHvA signals for Ce 0.9 Yb 0.1 CoIn 5 [inset of Figs. 1 and 2(a)] and no oscillations for the samples with Yb concentrations of x = 0.2, 0.3, and 0.5.…”

Effect of Disorder Induced by Heavy-Ion Irradiation on CeCoIn5 Superconductivity

“…The unusual properties of CeCoIn 5 have been investigated by various experiments such as specific heat [2,[4][5][6], magnetic susceptibility [5,7], resistivity [3,8], thermal conductivity [4], NMR T 1 measurement [9,10], and de Haas-van Alphen (dHvA) [8,11]. These results suggest an unconventional superconductivity in this complex compound.…”