Ferromagnetism Stabilized by Lattice Distortion at the Surface of the p-Wave Superconductor Sr2RuO4
R. Matzdorf,1
Z. Fang,3
Ismail,1
Jiandi Zhang,2
T. Kimura,3
Y. Tokura,34
K. Terakura,3
E. W. Plummer1*
Ferromagnetic (FM) spin fluctuations are believed to mediate the
spin-triplet pairing for the p-wave superconductivity in Sr2RuO4. Our experiments show that, at the
surface, a bulk soft-phonon mode freezes into a static lattice
distortion associated with an in-plane rotation of the RuO6
octahedron. First-principle calculations confirm this structure and
predict a FM ground state at the surface. This coupling between
structure and magnetism in the environment of broken symmetry at the
surface allows a reconsideration of the coupling mechanism in the bulk.
1 Department of Physics and Astronomy, The
University of Tennessee, Knoxville, TN 37996-1200, and Oak Ridge
National Laboratory (ORNL), Oak Ridge, TN 37831-6057, USA.
2 Department of Physics, Florida International
University, Miami, FL 33199, USA.
3 Joint Research
Center for Atom Technology (JRCAT), Tsukuba 305-0046, Japan.
4 Department of Applied Physics, University
of Tokyo, Tokyo 113-0033, Japan.
*
To whom correspondence should be addressed. E-mail:
eplummer{at}utk.edu
