Abstract
The tetragonal CeCoIn5 is an unconventional d -wave heavy-fermion superconductor with Tc =2.3 K. Strong Pauli limiting causes a first-order superconducting transition for fields close to Hc2 (0) and evidence for a Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state has been found at low temperatures. Here, we present a study of the in-plane angular dependence of the upper critical field. At T=0.1 K a fourfold oscillation of 1.2% amplitude with maxima along the [100] direction is observed. This points toward a d x2 - y2 order-parameter symmetry. The data are compared with theoretical calculations including the FFLO state and a tiny anisotropy of the g factor.
Original language | English |
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Article number | 134511 |
Journal | Physical Review B - Condensed Matter and Materials Physics |
Volume | 74 |
Issue number | 13 |
DOIs | |
State | Published - 2006 |
Externally published | Yes |