We report the observation of a magnetic polarization of the O 2p states in YMn2O5 through the use of soft x-ray resonant scattering at the oxygen K edge. Remarkably, we find that the temperature dependence of the integrated intensity of this signal closely follows the macroscopic electric polarization, and hence is proportional to the ferroelectric order parameter. This is in contrast with the temperature dependence observed at the Mn L3 edge, which reflects the Mn magnetic order parameter. First-principles calculations provide a microscopic understanding of these results and show that a spin-dependent hybridization of O 2p and Mn 3d states results in a purely electronic contribution to the ferroelectric polarization, which can exist in the absence of lattice distortions.
Read the article: Physical Review Letters
S. Partzsch1,2, S. B. Wilkins2, J. P. Hill2, E. Schierle3, E. Weschke3, D. Souptel1, B. Büchner1, and J. Geck1
1Leibniz Institute for Solid State and Materials Research IFW Dresden, Helmholtzstrasse 20, 01069 Dresden, Germany
2Condensed Matter Physics and Material Science Department, Brookhaven National Laboratory, Upton, New York, 11973 USA
3Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Str. 15, 12489 Berlin, Germany
Received 23 May 2011; published 25 July 2011