Exploring the fragile antiferromagnetic superconducting phase in CeCoIn5

TL;DR

This paper investigates the high-field magnetic and superconducting phases of CeCoIn5, revealing a fragile antiferromagnetic order that depends on the magnetic field orientation and disappears above a certain angle.

Contribution

It demonstrates the existence and orientation dependence of antiferromagnetic order within the superconducting state of CeCoIn5, clarifying its relation to high-field anomalies.

Findings

Antiferromagnetic order appears at high fields with a specific wavevector.

Magnetic order persists as the field is rotated out of the basal plane.

The magnetic moment disappears above 17 degrees of field tilt.

Abstract

CeCoIn5 is a heavy fermion Type-II superconductor which exhibits clear indications of Pauli-limited superconductivity. A variety of measurements give evidence for a transition at high magnetic fields inside the superconducting state, when the field is applied either parallel to or perpendicular to the c axis. When the field is perpendicular to the c axis, antiferromagnetic order is observed on the high-field side of the transition, with a magnetic wavevector of (q q 0.5), where q = 0.44 reciprocal lattice units. We show that this order remains as the magnetic field is rotated out of the basal plane, but the associated moment eventually disappears above 17 degrees, indicating that the anomalies seen with the field parallel to the c axis are not related to this magnetic order. We discuss the implications of this finding.