Antiferromagnetic Phases in the Fulde-Ferrell-Larkin-Ovchinnikov State of CeCoIn_5

TL;DR

This paper uses Ginzburg-Landau theory to analyze antiferromagnetic order within the FFLO superconducting state of CeCoIn_5, revealing multiple magnetic phases influenced by FFLO nodal planes and comparing theoretical phase diagrams with experimental data.

Contribution

It introduces a two-component Ginzburg-Landau model to describe incommensurate AFM order in the FFLO state of CeCoIn_5, highlighting the role of AFM moment pinning and phase diagram variations.

Findings

Multiple AFM phases emerge due to pinning by FFLO nodal planes.

Theoretical phase diagrams are consistent with NMR and neutron scattering data.

Incommensurate AFM order is characterized by specific wave vectors in CeCoIn_5.

Abstract

The antiferromagnetic (AFM) order in the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) superconducting state is analyzed on the basis of a Ginzburg-Landau theory. To examine the possible AFM-FFLO state in CeCoIn_5, we focus on the incommensurate AFM order characterized by the wave vector Q = Q_{0} \pm q_inc with Q_0 =(\pi,\pi,\pi) and q_inc \parallel [110] or [1-10] in the tetragonal crystal structure. We formulate the two component Ginzburg-Landau theory and investigate the two degenerate incommensurate AFM order. We show that the pinning of AFM moment due to the FFLO nodal planes leads to multiple phases in magnetic fields along [100] or [010]. The phase diagrams for various coupling constants between the two order parameters are shown for the comparison with CeCoIn_5. Experimental results of the NMR and neutron scattering measurements are discussed.