Fermi surface of the heavy-fermion superconductorCeCoIn5:The de Haas–van Alphen effect in the normal state

Abstract

Measurements of the de Haas-van Alphen effect in the normal state of the heavy-fermion superconductor CeCoIn 5 have been carried out using a torque cantilever at temperatures ranging from 20 to 500 mK and in fields up to 18 T. Angular-dependent measurements of the extremal Fermi surface areas reveal a more extreme two-dimensional sheet than is found in either CeRhIn 5 or CeIrIn 5 . The effective masses of the measured frequencies range from 9 to 20m*/m 0 .

Superconductivity and Non-Fermi-Liquid Behavior in the Heavy-Fermion Compound CeCo1−xNixIn5

“…T max is found to increase with increasing x, suggesting that the energy scale of the coherent heavy-fermion state becomes large with doping Ni. The increase in T max is similar to those observed in Snand Pt-doped CeCoIn 5 , but different from the decrease in T max found in the Cd, Hg, and Zn substitutions. 29,32,35) These opposite variations would mainly be attributed to the sign of the doped charge carrier in these compounds, as pointed out previously.…”

“…At this critical Sn concentration, the NFL behavior is realized at zero magnetic field, correspond-ing to the T -linear dependence in electrical resistivity and the − ln T divergence in specific heat divided by temperature. The similarity of the NFL behaviors between CeCo(In,Sn) 5 and pure CeCoIn 5 indicates that the AFM quantum critical fluctuation is still enhanced in CeCo(In,Sn) 5 , whereas no AFM ordering is observed in a wide Sn concentration range. Furthermore, it is suggested that these features would be related to the two-dimensional nature, since the X-ray absorption study revealed that most of the doped Sn ions occupy the CeIn layer located at the tetragonal basal plane.…”

“…Furthermore, it is suggested that these features would be related to the two-dimensional nature, since the X-ray absorption study revealed that most of the doped Sn ions occupy the CeIn layer located at the tetragonal basal plane. 34) In contrast to this suggestion, it is argued from the similarity in the suppression of the SC order between Ce(Co,Pt)In 5 and CeCo(In,Sn) 5 that the effect of the impurity on the SC order is independent of the occupied impurity positions and layers. 35) The suppression of the SC order is also observed in pure CeCoIn 5 under pressure, 36) but the usual Fermi-liquid state instead of the NFL state is stabilized at the critical pressure of the SC order.…”

“…Among the Ce-based heavy-fermion superconductors, CeCoIn 5 shows particularly intriguing properties concerning the SC and the AFM quantum critical phenomena. This compound has a primitive tetragonal crystal structure (the HoCoGa 5 -type structure) composed of the stacking sequence of CeIn-In 2 -Co-In 2 layers along the c-axis [inset of Fig.…”

“…[13][14][15][16][17][18] Furthermore, the existence of the AFM-QCP at ∼ H c2 is strongly suggested from the observations of the NFL behavior in the paramagnetic phase above H c2 , including the − ln T divergence in specific heat divided by temperature, the T -linear dependence in magnetization, and electrical resistivity. 10,19,20) In fact, the long-range AFM orders are generated by substituting the ions for the elements in CeCoIn 5 , such as Nd for Ce, 21,22) Rh for Co, [23][24][25][26] and Cd, Hg, and Zn for In. [27][28][29][30] In contrast to the doping effect by those ions, the substitution of Sn for In simply suppresses the SC phase without generating the AFM order.…”