Low-temperature ferroelectric phase and magnetoelectric coupling in underdoped La2CuO4+x

Authors: Z. Viskadourakis, I. Radulov, A. P. Petrović, S. Mukherjee, B. M. Andersen, G. Jelbert, N. S. Headings, S. M. Hayden, K. Kiefer, S. Landsgesell, D. N. Argyriou, and C. Panagopoulos

Published in: Phys. Rev. B 85, 214502, 2012.

We report the discovery of ferroelectricity below 4.5 K in highly underdoped La2CuO4+x accompanied by slow charge dynamics which develop below T ∼ 40 K. An anisotropic magnetoelectric response has also been observed, indicating considerable spin-charge coupling in this lightly doped parent high-temperature copper-oxide superconductor. The ferroelectric state is proposed to develop from polar nanoregions, in which spatial inversion symmetry is locally broken due to nonstoichiometric carrier doping.

DOI: 10.1103/PhysRevB.85.214502