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Magnetoelectric coupling in multidomain antiferromagnet Cu3TeO6

Multiferroic materials are a special class of solid- state compounds in which at least two types of orders simultaneously coexist. Among all, the magnetoelectric (ME) multiferroics in which the electric and magnetic order coexist are of particular importance in the fundamental research of interactions between electron charge and spin as well as lattice and orbital degrees of freedom. Moreover, some poorly understood complex excitations like electromagnons can exist in these materials [1, 2]. The family of antiferromagnets with multidomain structure is of particular interest here because they represent an opportunity to examine the dynamics of domains and domain walls, their motion, creation, or destruction, as well as to examine the role of ME effect. A member of the mentioned family is copper tellurium oxide, Cu3TeO6 which has a cubic crystal structure with a three-dimensional magnetic lattice in which copper ions form hexagons with shared vortices [3, 4]. The long-range antiferromagnetic arrangement, which occurs below TN = 61 K, is either collinear or has a small spin inclination. The high cubic symmetry of this material allows eight (4x2) antiferromagnetic domains. Considering the magnetic lattice, there are two possible explanations for the magnetoelectric response. A canted antiferromagnetic arrangement could yield toroidal domains each of which, with the application of a magnetic field, would have electric polarization in different directions. On the other hand, a collinear antiferromagnetic arrangement would break the symmetries of the inversion of both space and time which could explain the ME response [4]. In order to further investigate ME properties in Cu3TeO6 we performed static electric polarization and dynam-ic dielectric spectroscopy studies in an external magnetic field up to 5 T for a few different directions of electric polarization and magnetic field. Electric polarization was carried in fields up to 4 kV/cm. Together with previously shown magnetic properties [4] our measurements suggest that Cu3TeO6 is electric and magnetic field-induced ferroelectric, but the allowed magnetic point group cannot explain that linear magnetoelectric effect. Therefore, additional experimental and theoretical studies are needed to further understand the origin of linear ME coupling and the role of quantum effects in this material. [1] Dong, S. et al., Advances in Physics 64:5-6, 519-626, (2015) [2] Fiebig, M.et al., Nature Reviews Materials, 1(8), 16046, (2016) [3] Wang, D. et al., Phys. Rev.B 99, 035160, (2019) [4] Herak, M. et al., J. Phys.: Condens. Matter 17, 766, (2005)

magnetoelectric coupling ; antiferromagnets ; domains ;

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