Multiferroicity in Li Cu2 O2 single crystals is studied using resonant soft x-ray magnetic scattering, hard x-ray diffraction, heat capacity, magnetic susceptibility, and electrical polarization. Two magnetic transitions are found at 24.6 K (T1) and 23.2 K (T2). Our data are consistent with a sinusoidal spin structure at T2 <T< T1 and with a helicoidal spin structure at T< T2, giving rise to ferroelectricity. Surprisingly, above T2, the correlation lengths of the spin structures increase as the temperature increases with dramatic changes of ∼42% occurring along the c axis.
Bibliographical noteFunding Information:
We acknowledge M. Mostovoy for helpful discussions and financial support by the Helmholtz Association VH-FZ-007, DFG Ru 773/2-3, DE-FG02-06ER46285, NSLS No. DE-AC02-98CH10886, the Canadian funding agencies: NSERC, CIAR, and CFI, NSF-MDR-0405682.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy (miscellaneous)