Strong anisotropic spin-dipole coupling in electron-withdrawing Br-based system Cu₂(OH)₃Br

The compound Cu₂(OH)₃Br, belonging to an interesting hydroxyl salts of potential interests, crystallizes in monoclinic structure. This system consists of quasi-1D Cu-chains and undergoes complex antiferromagnetic ordering below around 10 K, with a magnetic field (H) induced spin-flop transitions below ordering. Here, we have investigated the detailed dielectric behavior of single crystalline compound in different orientations. We show that the temperature dependent dielectric constant clearly traces the magnetic ordering in presence of magnetic field, indicating the presence of magnetodielectric (MD) coupling. The MD coupling is further confirmed by isothermal H-dependent dielectric constant which captures the spin-flop transitions. These features are ascribable to electron withdrawing Br-atom to break the spatial inversion symmetry of the Cu-system, which creates local dipole moment and thereby governs strong MD coupling. This will create a path to design new magnetoelectric materials.