title: Magnetoelectric effect and phase transitions in CuO in external magnetic fields.
abstract: Apart from being so far the only known binary multiferroic compound, CuO has a much higher transition temperature into the multiferroic state, 230 K, than any other known material in which the electric polarization is induced by spontaneous magnetic order, typically lower than 100 K. Although the magnetically induced ferroelectricity of CuO is firmly established, no magnetoelectric effect has been observed so far as direct crosstalk between bulk magnetization and electric polarization counterparts. Here we demonstrate that high magnetic fields of ≈ 50 T are able to suppress the helical modulation of the spins in the multiferroic phase and dramatically affect the electric polarization. Furthermore, just below the spontaneous transition from commensurate (paraelectric) to incommensurate (ferroelectric) structures at 213 K, even modest magnetic fields induce a transition into the incommensurate structure and then suppress it at higher field. Thus, remarkable hidden magnetoelectric features are uncovered, establishing CuO as prototype multiferroic with abundance of competitive magnetic interactions.
authors.affiliation: Hochfeld-Magnetlabor Dresden (HLD-EMFL), Helmholtz-Zentrum Dresden-Rossendorf, D-01314 Dresden, Germany.
authors.forename: Zhaosheng
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Institut Laue Langevin, 6 rue Jules Horowitz, Boîıte Postale 156, F-38042 Grenoble, France.
authors.forename: Navid
authors.initials: N
authors.lastname: Qureshi
authors.affiliation: Hochfeld-Magnetlabor Dresden (HLD-EMFL), Helmholtz-Zentrum Dresden-Rossendorf, D-01314 Dresden, Germany.|American University of the Middle East, College of Engineering and Technology, 54200 Egaila, Kuwait.
authors.forename: Shadi
authors.initials: S
authors.lastname: Yasin
authors.affiliation: Prokhorov General Physics Institute, Russian Academy of Sciences, ul. Vavilova 38, Moscow 119991, Russia.
authors.forename: Alexander
authors.initials: A
authors.lastname: Mukhin
authors.affiliation: SPSMS, UMR-E CEA/UJF-Grenoble 1, INAC, F-38054 Grenoble, France.
authors.forename: Eric
authors.initials: E
authors.lastname: Ressouche
authors.affiliation: Hochfeld-Magnetlabor Dresden (HLD-EMFL), Helmholtz-Zentrum Dresden-Rossendorf, D-01314 Dresden, Germany.
authors.forename: Sergei
authors.initials: S
authors.lastname: Zherlitsyn
authors.affiliation: Hochfeld-Magnetlabor Dresden (HLD-EMFL), Helmholtz-Zentrum Dresden-Rossendorf, D-01314 Dresden, Germany.
authors.forename: Yurii
authors.initials: Y
authors.lastname: Skourski
authors.affiliation: Instituto de Física, Universidade Federal do Rio Grande do Sul, Porto Alegre, 91501-970 Rio Grande do Sul, Brazil.|Departament de Física, Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain.
authors.forename: Julian
authors.initials: J
authors.lastname: Geshev
authors.affiliation: Prokhorov General Physics Institute, Russian Academy of Sciences, ul. Vavilova 38, Moscow 119991, Russia.
authors.forename: Vsevolod
authors.initials: V
authors.lastname: Ivanov
authors.affiliation: Institute of Solid State Physics, Bulgarian Academy of Sciences, 1784 Sofia, Bulgaria.
authors.forename: Marin
authors.initials: M
authors.lastname: Gospodinov
authors.affiliation: Departament de Física, Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain.|Institució Catalana de Recerca i Estudis Avançats, E-08010 Barcelona, Spain.
authors.forename: Vassil
authors.initials: V
authors.lastname: Skumryev