Coupled Superconducting and Magnetic Order in CeCoIn5
M. Kenzelmann,1,2
Th. Strässle,3
C. Niedermayer,3
M. Sigrist,4
B. Padmanabhan,3
M. Zolliker,1
A. D. Bianchi,5
R. Movshovich,6
E. D. Bauer,6
J. L. Sarrao,6
J. D. Thompson6
Strong magnetic fluctuations can provide a coupling mechanism
for electrons that leads to unconventional superconductivity.
Magnetic order and superconductivity have been found to coexist
in a number of magnetically mediated superconductors, but these
order parameters generally compete. We report that close to
the upper critical field, CeCoIn
5 adopts a multicomponent ground
state that simultaneously carries cooperating magnetic and superconducting
orders. Suppressing superconductivity in a first-order transition
at the upper critical field leads to the simultaneous collapse
of the magnetic order, showing that superconductivity is necessary
for the magnetic order. A symmetry analysis of the coupling
between the magnetic order and the superconducting gap function
suggests a form of superconductivity that is associated with
a nonvanishing momentum.
2 Laboratory for Solid State Physics, Eidgenössische Technische Hochschule (ETH) Zurich, CH-8093 Zurich, Switzerland.
3 Laboratory for Neutron Scattering, ETH Zurich, and Paul Scherrer Institute, CH-5232 Villigen, Switzerland.
4 Institut für Theoretische Physik, ETH Zurich, CH-8093 Zurich, Switzerland.
5 Département de Physique and Regroupement Québécois sur les Matériaux de Pointe, Université de Montréal, Montréal, Quebec H3C 3J7, Canada.
6 Condensed Matter and Thermal Physics, Los Alamos National Laboratory, Los Alamos, NM 87545, USA.
