Abstracts of LT23

Session 22aC Session 22aC

Ferromagnetism and superconductivity

J. Flouquet^a, A. Huxley^a, I. Fomin^a, J-P. Brison^b, A. Buzdin^c

^aCEA-Grenoble, DRFMC/SPSMS, 38054 Grenoble Cedex 9, France

^bCRTBT-CNRS, 38042 Grenoble Cedex 9, France

^cCentre de Physique Moleculaire Optique et Hertzienne, Universite Bordeaux 1, 33405 Talence, France

The interplay of ferromagnetism and superconductivity has been examined for conventional s wave superconductors two decades ago. The new feature is the discovery of superconductivity in the ferromagnetic domain of itinerant electrons close to the critical density where long range magnetic order collapses (UGe₂, URhGe, ZrZn₂). An appealing proposal is the occurence of unconventional triplet pairing mediated by electronic interactions. New features may occur as spontaneous vortex state, weak link at the interface of magnetic domains...We will review the experimental situation including the normal phase properties and describe the different theoretical proposals.

22aC2 paper-pdf

Magnetism and Unconventional Superconductivity in Ce_nM_mIn_3n+2m Heavy-Fermion Crystals

J. D. Thompson^a, M. Nicklas^a, A. Bianchi^a, R. Movshovich^a, A. Llobet^a, W. Bao^a, A. Malinowski^a, M. F. Hundley^a, N. O. Moreno^a, P. G. Pagliuso^a, J. L. Sarrao^a, S. Nakatsuji^b, Z. Fisk^b, E. Lengyl^c, N. Oeshler^c, G. Sparn^c, F. Steglich^c

^aLos Alamos National Laboratory, Los Alamos, NM 87545 USA

^bNHMFL, Florida State University, Tallahassee, FL 32310 USA

^cMax-Planck-Institute for Chemical Physics of Solids, Dresden, D-01187 Germany

Antiferromagnetism and unconventional superconductivity in the family of heavy-fermion compounds Ce_nM_mIn_3n+2m (M=Rh, Ir, Co) are influenced by their layered, tetragonal crystal structure. We review magnetic and superconducting properties of these compounds and evidence for d-wave superconductivity that develops in proximity to antiferromagnetic quantum criticality.

22aC3

New forms of quantum order in strongly interacting electron systems (tentative)

Siddharth S. Saxena

Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, United Kingdom

We have been investigating quantum phase transitions and new forms of quantum order in strongly interacting electron systems at low temperatures, high pressures and high magnetic fields. This work has led to the observation of the first examples of superconductivity in itinerant-electron ferromagnets. The superconducting states observed on the border of magnetism are also poorly understood and would appear to require descriptions beyond that offered by the standard models.

22aC4

Unconventional superconductivity and quasi-2D spin fluctuations in heavy-fermion compounds Ce(Ir, Rh,Co)In₅

G.-q. Zheng^a, K. Tanabe^a, Y. Kawasaki^a, S. Kawasaki^a, Y. Kitaoka^a, Y. Onuki^b, J. Sarrao^c

^aDepartment of Physical Science, Osaka University, Osaka 560-8531, Japan

^bDepartment of Physics, Osaka University, Osaka 560, Japan

^cLos Alamos National Lab., NM 87545, USA

We report extensive NQR studies on the new heavy fermion superconductors Ce(Ir, Rh, Co)In₅. We find that the superconductivity is of unconventional type with line-node gap, and that CeIrIn₅ is located in close proximity to the quantum critical point (QCP) with strong quasi-2D magnetic fluctuations. We also find that the increase of T_c by substituting Rh for Ir /Co is due to a change in the magnetic fluctuations and that CeRh_0.5Ir_0.5In₅ and CeCoIn₅ sit right on the QCP. Based on these results, we discuss the interrelation between superconductivity and the magnetic fluctuations near the QCP.