Hyperfine fields and magnetic structure in the B phase of CeCoIn5

Abstract

We re-analyze Nuclear Magnetic Resonance (NMR) spectra observed at low temperatures and high magnetic fields in the field-induced B-phase of CeCoIn5. The NMR spectra are consistent with incommensurate antiferromagnetic order of the Ce magnetic moments. However, we find that the spectra of the In(2) sites depend critically on the direction of the ordered moments, the ordering wavevector and the symmetry of the hyperfine coupling to the Ce spins. Assuming isotropic hyperfine coupling, the NMR spectra observed for H||[100] are consistent with magnetic order with wavevector Q=pi((1+delta)/a,1/a,1/c) and Ce moments ordered antiferromagnetically along the [100] direction in real space. If the hyperfine coupling has dipolar symmetry, then the NMR spectra require Ce moments along the [001] direction. The dipolar scenario is also consistent with recent neutron scattering measurements that find an ordered moment of 0.15 mu_B along [001] and Q_n=pi((1+delta)/a,(1+delta)/a,1/c) with incommensuration delta = 0.12 for field H||[1-10]. Using these parameters, we find that a hyperfine field with dipolar contribution is consistent with findings from both experiments. We speculate that the B phase of CeCoIn5 represents an intrinsic phase of modulated superconductivity and antiferromagnetism that can only emerge in a highly clean system.

10 pages, 8 figures, QFS 2009

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Cited by in corpus (11)

• Anomalous Upper Critical Field in CeCoIn_5/YbCoIn_5 Superlattices with a Rashba-type Heavy Fermion Interface
• Evolution of Paramagnetic Quasiparticle Excitations Emerged in the High-Field Superconducting Phase of CeCoIn5
• Exploring the fragile antiferromagnetic superconducting phase in CeCoIn5
• Commensurate Antiferromagnetism in CePt2In7, a Nearly Two-Dimensional Heavy Fermion System
• Coexistence of superconductivity and incommensurate magnetic order
• Impurity-induced antiferromagnetic order in Pauli-limited nodal superconductors: application to heavy fermion CeCoIn5
• Vortex lattice studies in CeCoIn5 with H perpendicular to c
• Structure of magnetic order in Pauli limited unconventional superconductors
• Microscopic coexistence of a two-component incommensurate spin density wave with superconductivity in underdoped NaFe${}_{0.983}$Co${}_{0.017}$As
• Hyperfine Couplings as a Probe of Orbital Anisotropy in Heavy Fermion Materials
• NMR Studies of Field Induced Magnetism in CeCoIn${}_5$