Magnetic structure of Cd-doped CeCoIn5

TL;DR

This study reveals that Cd-doped CeCoIn5 exhibits commensurate antiferromagnetic order coexisting with superconductivity, providing new insights into the magnetic structure and its relation to superconductivity in CeTIn5 compounds.

Contribution

First direct determination of the magnetic structure in Cd-doped CeCoIn5 showing commensurate order, contrasting with related compounds, and elucidating the interplay between magnetism and superconductivity.

Findings

Magnetic order appears only at the wave vector Q_AF = (1/2,1/2,1/2).

Magnetic intensity remains nearly unchanged across the superconducting transition.

The magnetic order is commensurate, unlike the incommensurate order in CeRhIn5.

Abstract

The heavy fermion superconductor CeCoIn5 is believed to be close to a magnetic instability, but no static magnetic order has been found. Cadmium doping on the In-site shifts the balance between superconductivity and antiferromagnetism to the latter with an extended concentration range where both types of order coexist at low temperatures. We investigated the magnetic structure of nominally 10% Cd-doped CeCoIn5, being antiferromagnetically ordered below T_N=3 K and superconducting below T_c=1.3 K, by elastic neutron scattering. Magnetic intensity was observed only at the ordering wave vector Q_AF = (1/2,1/2,1/2) commensurate with the crystal lattice. Upon entering the superconducting state the magnetic intensity seems to change only little. The commensurate magnetic ordering in CeCo(In1-xCdx)5 is in contrast to the incommensurate antiferromagnetic ordering observed in the closely related compound CeRhIn5. Our results give new insights in the interplay between superconductivity and magnetism in the family of CeTIn5 (T=Co, Rh, and Ir) based compounds.