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  Viskadourakis, Z.; Radulov, I.; Petrovic, A.P.; Mukherjee, S.; Andersen, B.M.; Jelbert, G.; Headings, N.S.; Hayden, S.M.; Kiefer, K.; Landsgesell, S.; Argyriou, D.N.; Panagopoulos, C.: Low-temperature ferroelectric phase and magnetoelectric coupling in underdoped La₂CuO_4+x. Physical Review B 85 (2012), p. 214502/1-8

10.1103/PhysRevB.85.214502
Open Access Version (externer Anbieter)

Abstract:
We report the discovery of ferroelectricity below 4.5 K in highly underdoped La2CuO4+x accompanied by slow charge dynamics which develop below T similar to 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.