Field-induced ferromagnetism due to magneto-striction in 1-D helical chains

Abstract

Two homochiral copper(II) helices, [Cu(μ_1,3-N₃)(L¹)]_n (1) and [Cu(μ_1,3-NCO)(L²)]_n (2), with end-to-end pseudohalide bridges, were synthesized using two N₂O donor achiral Schiff bases via spontaneous chiral resolution. Field-induced ferromagnetic ordering due to magneto-striction in homochiral 1-D helix [Cu(μ_1,3-N₃)(L¹)]_n (1) is reported for the first time. At temperatures below 5.5 K, under a magnetic field of 1 T, orthogonality between the magnetic orbitals of copper centres increases significantly due to the contraction of lattice parameters, giving rise to long-range ferromagnetic ordering in the helical chain. The magneto-dielectric results are also indicative of the observed magneto-striction effect in the present complex 1. We believe that this study will uncover a new way to invoke long-range ferromagnetic ordering in 1-D helical chains.